sponding with the two views given for D. ampelophila in figures 1 and 2. The eight genes lie in four groups at the four apices of the figure, in groups of 2, 3, 2, and 1 respectively. The figure has a very definite and rigid form, for geometrical reasons. Three additional linkage relations should be known to determine fully the position of certain of the genes within their respective groups. These are magenta-hairy, glazed-rugose, and frayed-forked (or frayed-glazed), where the figures show connecting wires to be wanting.2 Given these missing connections, the form of the model would be very fully determined in every detail. Any newly discovered sex-linked gene of D. virilis having been located with reference to three of these eight genes, its rela tions to all the others could be predicted by direct measurement from the model. 1 Metz, C. W., Genetics, 3, 1918, (107-134). 2 From measurement of the model, it may be predicted that the cross-over percentage between magenta and hairy will be about 4 or 5, and the glazed-rugose percentage about the same, probably a little greater. The position of frayed in the system is not fully determined, as only two linkage relations of frayed are known. But it may be predicted, from measurement, that the frayed-forked cross-over percentage will lie between 39 and 41, and that frayed-glazed will lie between 43 and 46, provided of course that the relations given in table 1 have been determined with sufficient accuracy. THE CAUSE OF PROLIFERATION IN BEGONIA PHYLLOMANIACA BY ERWIN F. SMITH LABORATORY OF PLANT PATHOLOGY, UNITED STATES DEPARTMENT OF AGRICULTURE Read before the Academy, November 18, 1918 The cause of the excessive production of adventive shoots on the leaves and internodes of this plant (a very strange phenomenon) is attributed to excessive loss of water, due to woundings or other causes. Usually in regeneration the response is not far from the place of injury, here it may be at a long distance from the wounded part, e.g., roots wounded and response in the top of the plant, although a direct response from the injured part can also be obtained. The paper will be published in full in The Journal of Agricultural Research. The following is a synopsis: 1. Ordinary begonia leaves when detached from the plant and pegged down on moist sand develop roots and shoots from cut places and this method is used by gardeners for the propagation of begonias. Many other plants are propagated in this way, e.g., the hyacinth from bulb scales. 2. But the leaves and shoots of this begonia proliferate while still attached to the plant. 3. They will proliferate on the plant very freely when wounded, making small forests of shoots on the thickened red lips of the wound if the wounds are made in quite young tissues, but not otherwise (young leaf blades were used). 4. They will frequently proliferate in the top parts of cuttings (on leaves and internodes) especially if the cuttings are dried for a day or two before planting. 5. They will proliferate most astonishingly at the top of the plant (both from leaves and internodes) if the roots are wounded, but here again only quited young tissues can be shocked into the production of such shoots. This is the most striking fact I have discovered, viz., that the prolification may occur at a long distance from the place of wounding and must be from young tissues. So far as known to the writer, it is the first example of response of this sort at a distance from the point of injury. 6. I have also some evidence that leaves will proliferate locally under colonies of sucking insects (mealy bug, white fly), also that withholding water from the plant for a few days will cause it to proliferate. 7. The nature of the shock appears to lie in the sudden interruption of the water current which is conceived to cause cell-precipitates or plasmolysis of young totipotent cells which begin to grow when they have recovered from the shock. 8. The prolification at times is so much like a forest that one must assume that the whole surface (epidermis) of immature shoots is full of cells capable of growing into new plants if properly shocked but that as the tissue matures these cells either lose their power of response, or become more perfectly protected. 9. These adventive shoots, for the most part, perish quickly and cannot be regarded as branches, since they have no initial connection with the ordinary cambium, or xylem-phloem of the mother plant. They are rather to be classed with filial teratomas. Later, a small proportion of them establish connections with the conductive tissues of the mother and persist, i.e., become abnormally situated branches. 10. My observations contradict those of Prillieux and confirm those of Verlot and of Caruel that buds may arise from the ordinary trichomes. They may develop either from the base or the middle of acicular hairs. Such hairs arise from a red tissue, the other parts of the epidermis being green. I have also seen them developing from the base of glandular hairs which are abundant on the young internodes, but they are not restricted to these pairs. THE PERCENTAGE NUMBER OF METEORITE FALLS AND FINDS CONSIDERED WITH REFERENCE TO THEIR VARYING BASICITY BY GEORGE P. MERRILL DEPARTMENT OF GEOLOGY, UNITED STATES NATIONAL MUSEUM, WASHINGTON, D. C. Communicated by C. G. Abbot, January 9, 1919 Various compilations relating to time and distribution of meteorite falls have been made with a view of correlating them with periodic showers, but with, thus far, the only result of showing that there is no apparent connection between them.1 Viewing the subject from a geological standpoint, that is, from the standpoint of an earth made up by the gradual accumulation of meteoric materials, and considering also the apparent more basic nature of the earth's interior as compared with the outer portion, I have thought it possible some light might be thrown upon it through a consideration of the percentages of actually observed falls and the relative basicity of their materials. The results of such consideration are given below:2 Of the total 367 known meteoric irons there were seen to fall but 17, or less than 5%. These are essentially metallic; ultra basic. Of the 31 known stony irons variously classed as Lodhranites, Pallasites and Mesosiderites, carrying at times as high as 50% metal, there were seen to fall but 5, or in round numbers 16%. Of the 370 known stones composed mainly of silicate minerals, with chondritic structure, carrying from 5 to 25% metal (Howarditic chondrites to Ureilites inclusive), there were seen to fall 322, or 87%. Of the 21 calcium-aluminum-rich stones, carrying less than 1% metal, free of chondrules, and variously classed as Angrites, Eukrites, Shergottites and Howardites, there were seen to fall 20, or 95%. Of the 12 magnesia rich stones essentially free from metal without chondrules and classed as Bustites, Chassignites, Chladnites and Amphoterites, the most acidic types known, there were seen to fall 12, or 100%. As there is little reason for supposing that falls of one kind are not as conspicuous as those of another, it would seem a fair assumption that those of which the seen percentage was the smallest were the earliest, perhaps largely prehistoric. Hence arises the thought of a gradual decreasing basicity or what is the same thing, increasing acidity of accumulated materials, as time goes on. While it would seem absurd to claim that such a change could manifest itself perceptibly during the few years of observation, it is nevertheless worthy of note that, however much uncertainty is attached to the period of fall of upwards of 95% of the known meteoric irons, the stones of the last two classes mentioned, which are of the most acidic type and with one or two exceptions are iron free, have fallen within a period of a little more than one hundred years. Following out the same line of thought, it would seem possible that the thousands of meteors which are known to enter our atmosphere daily and yet leave no record of their fall, might be products of a still further differentiation of cosmic matter (or perhaps derived from an entirely different source) and of such eminently combustible material as to be largely consumed in their flight. Additional interest is attached to this suggestion from the fact that there are known but eight carbonaceous meteorites, i.e., eight stones in which an uncombined carbon (or possibly hydrocarbon) occurs in such quantities as to give them a distinctive character and which, therefore, might be considered liable to destruction by heat while passing through our atmosphere. All of these eight were seen to fall, the first, that of Alais, France, in 1834 and the latest, that of Indarch, India, in 1891. It is possible to account for some of the facts here given on the assumption that many meteorites are of an extremely perishable nature, and unless seen to fall and sought for immediately, likely to become destroyed through dis integration. Further than this, a meteoric stone would be less likely to attract the attention and curiosity of the ordinary individual than would an iron. So far as the first possibility is concerned, I think that all who have had to do with meteorite collections will agree that as a general rule the irons, through their susceptibility to a damp atmosphere and consequent rusting, require much more attention for their preservation than do the stones. The second possibility is, however, one that must be given consideration. 1 See Chapter IV of Farrington's Meteorites, Chicago, 1915. 2 The figures here given relative to number of falls are believed to be substantially correct up to 1916. Accurate statistics since that date are not available. It would be a natural supposition that the fall of an iron would be less noticeable than that of a stone since the former would be less liable to break up-explode in its passage through the atmosphere. Unfortunately, the literature is not sufficiently explicit on this point to bear out the supposition. Hidden, to be sure, states that the fall of the Mazapil iron was accompanied only by a loud sizzing sound, there being no explosion or loud detonation. On the other hand, Kunz states that the fall of the Cabin Creek iron was "accompanied by a very loud report which caused the dishes to rattle," and the fall of the Nedagolla iron is also stated to have been accompanied by an explosion. Accounts of other falls are either noncommittal on this point or equally contradictory, and it is evident accurate information is lacking. NOTE ON A CONTACT LEVER, USING ACHROMATIC BY CARL BARUS Communicated, December 27, 1918 1. Apparatus.-The method heretofore described for the measurement of small angles by the aid of the rectangular interferometer, lends itself conveniently for the construction of apparatus like the contact lever, or the spherometer. Having work needing such instruments in view, I designed the following simple apparatus for the purpose. Figure 1 is a plan of the design; figure 2 an elevation of the fork and appurtenances; figure 3 (plan) finally shows the same apparatus adapted for use as a spherometer. The interferometer receives the white light from a collimator at L. After the reflections and transmissions controlled by the mirrors M, M', N, N', and the auxiliary mirror mm', as indicated in the figure, the light is conveyed into the telescope at T for observation of the interferences. The mirror M', is on a micrometer with the screw s normal to its face. It is through the mirror mm' that the small angles are to be measured and this is therefore mounted at one end of the lever dc, capable of rotating around the long vertical axle aa, in the circular fork FF. The latter is rigidly mounted on the bed of the apparatus by aid of the stem I in the rear. The lever c is bent upward at right angles at d, and it is here that the mirror mm' is firmly |