Ine of -ies of The essels other s are the The dium capes tches bided time mall Rob snail ture erm over elop sts. con eral Enter Face the ing ter kin -me eir ere ree Con en in is al of st. p -i to s of 7. st t 4 mm. to 5 mm. it can be seen that the sexual dimorphism can be noted at a very early stage. Even in the smaller stages the males have a distinctly larger oral sucker than the females and the body is wider. Also early in develop ment the females show a larger space between the intestinal ceca in front of their point of union than do the males. As development proceeds the differences in size between the suckers of the sexes becomes more distinct. The males become broad and flat and finally the sides of the post-acetabular region curl up to form the gynæcophoric canal. In the females the body tends to become round in cross section and the width is constantly much less than that of males of the same age. A detailed description of this development will be made in a future publication. Fujinami and Nakamura2 in a paper published in Japanese antedate my findings on early sex dimorphism in Schistosoma japonicum. They were able to distinguish the sexes in specimens 0.5 mm. to 0.7 mm. in length, which developed in dogs. They laid especial emphasis on differences in the width of the body and in the character of the intestinal ceca as characters for distinguishing sex. The next question which arises in this connection is whether sexual dimorphism is present in schistosome cercaria. Although many workers have made studies and measurements of the cercaria of the human schistosomes no one has reported such differences. I have myself examined a number of cercariæ of S. japonicum with this point especially in mind without noting any dimorphism. Dr. S. Yokogawa, of the Medical College of Formosa, also informs me that he has made an extensive series of examinations and measurements of this cercaria in an attempt to find sexual differences without success. Since the cercaria of the human schistosomes are very small and can extend and contract their bodies to an unusual extent, slight size differences might escape notice in the living 2 Fujinami, A., and Nakamura, H., 1911, "A demonstration of some specimens showing the development of Schistosoma japonicum" (Japanese). Bio ri Gaku Kaishi, Vol. 1. specimens and be difficult if not impossible to detect in measurements of preserved material. Recently in some studies on a species of schistosome cercaria with eyespots from Plan orbis trivolvis from Douglas Lake, Michigan I have been able to demonstrate two distinc size types. This difference in size came to my attention first when I found that the curve plotted from the measurements of cercaria from a number of infected snails was dis More tinctly bimodal. extensive studies showed that the cercariæ of this species fel into two distinct size groups. I further found from measurements of the cercaria from eleven infested snails that in the cercaria coming from a single snail only one of the size types was represented. The difference in size was so great between these two types tha it could be recognized with the naked eye when free-swimming cercariae of the two types were placed in separate bottles. Measure ments of the length of the body of the larger type showed a range of variation from 0.234 mm. to 0.28 mm. while in the smaller type the range was from 0.207 mm. to 0.24 mm Other measurements of the body and tail which in this species is unusually large showed like differences. The adult into which this cercaria develops is not known, although unsuccessful attempts were made to introduce it into ducks and rats. An analysis of its structure, however, places it near to the human schistosomes in the family Schisto somida. This relationship means that in all probability in the adult stage of this species the sexes are separate. I therefore interpret the size differences in this species of cercaria as a sexual dimorphism. If this view is ac cepted the fact that in one infested snail only one of the types of cercaria is represented immediately becomes very significant. A more detailed account of the dimorphism of this species of cercaria will be published later in connection with a study of its structure and activities. 228 This author found that in twenty-six out of According to this hypothesis sex in the ORIGIN OF POTAT A YEAR ago the writer cal the threatened introduction States of two more crop pests, Puccinia Pittieriana, and t Puccinia Arachidis.2 Since fungus has been found in one where all vestige of it was at The other fungus has not yet United States. During 1918 the potato abundant and harmful in station grounds at Ambato, F upon potatoes but even more This was the first report of t America, having previously b from the high lands of Cos potato alone. In Ecuador it preference for North Ameri the tomato. An excellent ill of the rust and its behavior, on its origin, was published i the Ambato station for Janu station botanist, Abelardo P the liberty to quote a few tences from this article, afte from the Spanish into an E The rust of the tomato and new disease, not only in our fi but also elsewhere. Not simply elty should interest us, but m virulence, its ease of propagat mous injuries that it occasion tions would seem to place it an ous maladies of cultivated crops The history of this rust [in t easily sketched. The year 1918 the date of its first appearand spring of that year we had very grave disturbances, by given the general name of pla plots from seed of North Am varieties most attacked were t Acme, Golden Queen and Nearly at the same time we n 1 Presented to the Mycologi Botanical Society of America a ing, December 29, 1920. 2 SCIENCE, 51: 246-247, Mar 8 Boletin de Agricultura Quin Figs. 1, 2, January, 1920. in the parcels of potatoes of the variety Calvache. Where did this new parasite come from? We Mr. Pachano informs me by letter that the disease was not so prominent during 1919 as it was in 1918, but had the same relative predominance on the tomato, especially on the North American varieties. He has also modified his views regarding its origin. We may assume, I think, that the susceptibility of North American varieties has no special significance in connection with the question of the native host or habitat. The snapdragon rust has been known since 1897, and has spread throughout the United States, but only recently has it been traced to its native Californian hosts. In fact I think we can safely assume that the appearance of the potato rust in the gardens of central Ecuador indicates that the rust can be found on uncultivated native plants in that same region. The Solanum rusts of tropical and semi-tropical America are numerous, but have been little studied, and those of Ecuador almost not at all. There is a rust described from Colombia on Sarache edulis, a close relative of Solanum, which much resembles the potato rust except that it has slightly larger spores. This same rust on another species of Sarache was found in the vicinity of potato rust on Mt. Irazú in Costa Rica by E. W. D. Holway, who tells me that the plant is common in gardens there, going by the name "yerba mora." There is also a very similar rust known on the wild Solanum triquetrum, a vine ranging southward from central Texas into the adjacent region of Mexico, but this form has slightly smaller spores than the potato rust. On actual trial can show if these forms can b transferred from one host to another, and the size of the spores is in anywise depender upon the host. A variation in spore-size apparently de pendent on the host is found to occur in th case of the snapdragon rust, and cases of suc size variation are known for other species some of them authenticated by pedigree cul tures. The spores from the potato and tomat are remarkably uniform in size. Whether th three forms of Solanaceous rusts here referre to are the same or not, it is fairly safe t predict that the potato rust has originated somewhere between Ecuador and Costa Rica on hosts native to the localities. SCIENTIFIC EVENTS A WORLD ATLAS OF COMMERCIAL GEOLOGY WITH the growth of American industries the known and the possible sources of our greater and more pressing interest. Even the supplies of raw materials have become of United States-most favored of nations in abundance and variety of raw materials-can not be self-sufficient; it must look beyond its shores for supplies as well as for markets. The study of the distribution of mineral raw materials and their relations to the promotion of trade and the control of industry is a branch of geology and may best be termed commercial geology. Under the complex requirements of present-day life no continent, not even North America, can be self-sustaining. It is no longer enough for us to make an inventory of the mineral wealth of the United States; we must supplement that inventory by a broad understanding of world demand and supply. To set forth graphically and to describe concisely the basic facts concerning both the present and the future sources of the useful minerals is the purpose of a World Atlas of Commercial Geology just 230 issued by the United States Geological Survey, Department of the Interior. The output of the essential minerals in 1913, the latest normal year, may at least be regarded as a measure of the "quick assets possessed by each nation, and the first part of the World Atlas of Commercial Geology has therefore been planned to show the distribution of mineral production in 1913. The practical value of this exhibit of the world's mineral assets is evident. Experience gained during the World War emphasizes the advantage of an adequate supply of raw materials close at hand, yet that there are certain economic limits to domestic independence in raw materials is clearly shown by the readjustments already made. The more facts we possess bearing upon the relative quantity and the relative availability of the mineral resources of our own and of other countries, the better able will be our captains of industry to decide whence they should derive their raw material. The mines of the United States should be looked upon primarily as tributary to the many mills, shops, and factories in which the skilled labor of the country may find its opportunity for a livelihood. The output of raw minerals measures only the first step in industry. More than a score of geologists have cooperated in the preparation of this atlas, which was first undertaken during the World War as a part of the task of keeping American industries supplied with raw material a byand is to be regarded therefore as product of the war-time activities of the Geological Survey. AWARDS OF THE LOUTREUIL FOUNDATION AMONG the awards made this year, as we (1) 10,000 francs to Charles Alluaud and to R. Jeannel, for the study of the zoological and botanical material collected by them in the high mountains of eastern Africa and for the publication of the results. (2) 5,000 francs to Jules Baillaud, for the es tablishment of a recording microph (4) 2,000 francs to Clément Coc (6) 4,000 francs to Justin Joll- (7) 7,000 francs to Louis Joubi cation of the results of the Frenc pedition. (8) 3,000 francs to the late Ju the publication (under the dire Bonnier) of a work on the flora a the neighborhood of Rheims. (9) 3,000 francs to Henri Br (10) 2,000 francs to A. Me- (12) 8,000 francs to the Zi-Ka- (14) 10,000 francs to G. Pruv vitza, directors of the Archives périmentale et générale, for this 】 (15) 6,000 francs to Alcide Ra lication of researches on the par mestic animals of Indo-China. (16) 4,000 francs to J. J. Rey tion of a botanical geography Pyrenees. (17) 10,000 francs to Maxim for researches relating to the chanical constants of metals int in the construction of agricultur (18) 12,000 francs to the Aca for the establishment of a cata and technical periodicals in the It was pointed out by the cou although the special object of th the promotion of original researc requests for assisting work to cording to a well-defined scheme ingly few in number. THE AMERICAN JOURNAL OF TROPICAL MEDICINE THE American Society of Tropical Medicine announces a new publication for physicians and research workers, to be known as The American Journal of Tropical Medicine. The announcement says: "The general experience of the medical sciences has fully demonstrated the advantages which accrue from the segregation of special subjects. A central organ for the prompt presentation of articles, that are now scattered over a wide field, or the lack entirely of a proper medium to turn to for publication, will be a great convenience to those interested in the study of tropical diseases, and also serve to stimulate the growth and development of the subject. The purpose of the new JOURNAL will be to serve as a medium for the dissemination of reliable information from every source, with regard to the clinical and other phases of the nature, treatment, and prevention of tropical diseases." The JOURNAL will be published bi-monthly by the Williams and Wilkins Company, Baltimore, Md. The transactions of the annual meetings of the American Society of Tropical Medicine will be published in the Journal. Various reports, lists of members, and such other information as may be suitable will also appear. Other papers, whether from members or not, will also be published. The following are members of the editorial Editor: H. J. Nichols, Medical Corps, U. S. Washington, D. C.; K. F. Meyer, Universit of California, San Francisco, Calif.; E. B Ransom, Department of Agriculture, Wash ington, D. C.; R. P. Strong, Harvard Uni versity; A. J. Smith, University of Pennsyl vania; E. R. Stitt, surgeon general, U. S Navy; W. S. Thayer, Johns Hopkins Uni versity; E. J. Wood, Wilmington, N. C. Ex-officio Advisory Editorial Board, Th American Society of Tropical Medicine: J. M Swan, president; K. F. Meyer, first vice-presi dent; V. G. Heiser, second vice-president S. K. Simon, secretary and treasurer; A. J Smith, assistant secretary and treasurer George Dock, councillor; C. L. Furbush councillor; J. F. Siler, councillor; J. H White, councillor; C. S. Butler, councillor. THE SCIENTIFIC STAFF OF THE AMERICAN IN appointing the scientific staff of the American Museum of Natural History for 1921, the board of trustees has made a number of changes and promotions, some of which have already been noted in SCIENCE. The senior curator of the staff, Dr. Joel A. Allen, has been promoted to be honorary curator of mammals, in order that he may devote his entire time to his researches. Dr. Allen is in his eighty-third year and for more than 35 years has been the head of the department of mammalogy. This relief from the responsibility of administrative work comes as a welcome change to Dr. Allen, who speaks of his new appointment in the following language: I wish to express to you, and through you to the board of trustees, my deep appreciation of this honor, and of the privileges accompanying it, thus awarded me. It will be a great solace to me during such time as may remain to me for the prosecution of research work, which I am still able to pursue with unabated zest and pleasure. The trustees have created a new department designated as comparative anatomy and have appointed Dr. William K. Gregory to the curatorship as a recognition of Dr. Gregory's contributions to anatomy and vertebrate |