waves nor the sound gave any indication of the fundamental. Thus the node at the closed end of the pipe is a semi-node S, figure 2, while that nearer the open end is a full node SS, and the difference found is equivalent to the mean energy of the former and should be trebled. The duodecimal overtone was also obtained sharply.

=

Finally the temperature equivalent of the mechanical energy per fringe, computed either as Jcp At = pAp/p, or as At T(k/c-1) Ap/p comes out 1.5° C., if σ = 273°. Some years ago I tried to measure this with a bolometer-telephone device, but failed. This reason seems to be that in case of these rapid alternations, heat does not enter the wires appreciably.

Reed Pipes. Voice.-In the endeavor to obtain waves of larger amplitude, the device resorted to was a brass pipe 32 cm. long and 3 cm. in diameter, through which the component ray of the interferometer passed, provided with a tubulure about 1 cm. in diameter at its middle. This was then connected with flexible tubing to the reed box. The note was coarse like a bassoon.

With the flexible connector very short, the first experiments gave a display of enormous waves, 20 or 30 fringes high. I suspected that this could only be a direct mechanical effect of the sonorous reed on the interferometer. The reed pipe was, therefore, mounted on a separate scaffolding, entirely independent of the interferometer. The result was an immediate reduction of double amplitudes to a few fringes. On replacing the reed by an clarionette mouth piece, the results were similar.

The pipe was now moved, as a whole, out of the range of the rays of the interferometer and sounded. To my astonishment, strong waves were again produced, nearly as much so as when the pipe was in position for interference. In other words, these reed notes act directly on certain parts of the interferometer, and excite the parts selected by resonance.

To test this further, I made use of the voice, singing a foot or more away from the interferometer. At certain chest notes (b, c'), the fringe bands broke into marked waves near a fringe in double amplitude, the effect being absent from the remainder of the scale. A clarionette played about a yard or more from the interferometer evoked the following response: a b d'e' f'g' a'..f"

e..g

c'

0..0 strong stronger Max. strong weak 0 weak no response

1.2 fringes

The

Resonating pipes on the interferometer had no discernible effect. seat of receptivity is probably the iron base of the apparatus. Loading it depressed the maximum to b. A totally different interferometer, in a new location, showed the same behavior on the same base (lathe bed). In a third interferometer of different construction and on a different base, the clarionette e was most effective, b, c', f', a' marked the remaining

notes ineffective. I also constructed diapason pipes over 60 cm. long and 5 cm. in diameter, which were excited with my adjustable embouchure. The full c' obtained had the same direct effect on the interferometer as the clarionette. This discrepancy is exceedingly difficult to eliminate as it calls for a detection of the resonant member of the interferometer.

With the 1-foot diapason organ pipes used above, there is much less danger of direct influence. This is shown, for instance, in the balance obtained with nodes of opposite sign. Moreover, I made control experiments by blowing equipitched diapason pipes strongly in the neighborhood. There is even here liable to be a little response. The tendency to assume wave form may be recognized; but it is much smaller than the pipe note proper, and quite absent in the overtones. Finally, the elbowed pipe, figure 3, which blows away from the interferometer, was used for additional guarantee and for overtone nodes.

A PRELIMINARY NOTE ON THE RESULTS OF CROSSING CERTAIN VARIETIES OF NICOTIANA TABACUM

BY WILLIAM ALBERT SETCHELL, THOMAS HARPER GOODspeed and Roy ELWOOD CLAUSEN

DEPARTMENT OF BOTANY AND DIVISION OF GENETICS of the Department of AgriCULTURE, UNIVERSITY OF CALIFORNIA

Communicated January 10, 1921

In connection with a taxonomic study of the various species and varieties of Nicotiana, the authors became interested in the extremely varied assemblage of varieties, both botanical and commercial, included under the species N. Tabacum. The senior author ventured to suggest a preference for five type varieties as representative of the range of variation found within the species and possibly of fundamental importance as stem forms in the derivation of other varieties. A similar attempt to refer existing commercial varieties to derivation from a limited number of fundamental forms had previously been made both by Comes1 and Anastasia. These authors agreed in principle on the method of derivation of existing varieties, but they held conflicting views as to which particular forms should be recognized as fundamental. In all three cases the principle followed in attempting to unravel the problem of origin of cultivated forms was to determine which few historically old varieties possessed in various combinations all the characters exhibited by commercial varieties, and then to refer existing varieties to hybridization with resulting segregation and recombination of characters exhibited in the stem forms.

The senior author, having tentatively selected five such stem forms, thought it wise by actual genetic experimentation to determine what results would follow hybridization among them. The authors also found themselves in need of some definite information as to the Mendelian de

tails involved in character differences within the species. Accordingly three crosses were actually made and studied at some length. In some cases derivative lines were carried into the tenth hybrid generation. The three crosses, all in reciprocal, were made in 1909 as follows: (1) angustifolia x macrophylla, (2) calycina x virginica (Maryland) and (3) alba (White) x macrophylla. Detailed descriptions of the above-named varieties have been given by Setchell3 in a previous paper. In this article we shall confine our attention to the Mendelian results of the studies.

The Angustifolia-Macrophylla Series. In the angustifolia-macrophylla series an attempt was made to subject two character differences to Mendelian analysis, viz., the light pink flower color of angustifolia versus the red of macrophylla and the long-petioled leaf-base of angustifolia versus the sessile, broad leaf-base of macrophylla. The former of these contrasts proved to be a simple monogenic one, but the latter necessitated a complex Mendelian formulation.

Turning our attention to flower color first, F1 was pink-flowering but the intensity of coloration was distinctly greater than that of angustifolia. Ten F2 families containing a total of 490 plants consisted of 377 pinkflowering and 113 red-flowering plants. The pink-flowering segregants clearly gave evidence of the existence of two sub-classes differing in intensity of coloration. The count totalled 240 pink-flowering and 137 light pink-flowering individuals, a rough approximation to a 2:1 ratio. Very little reliance, however, can be placed upon this classification because of the evident intergrading of the two sub-classes. Separation into red and pink was clear and distinct. The F3 populations conformed to expectation based upon the F2 results, with the single exception noted below. Four F2 red-flowering selections gave 99 F3 plants all red-flowering. Of fifteen F2 pink-flowering selections ten gave progenies exhibiting segregation in conformance with the 3 pink: 1 red ratio, the actual totals being 187 pink: 60 red. Four F2 pink-flowering selections bred true for pink, the entire 89 F3 plants being pink. One population from an F2 pinkflowering selection yielded a progeny consisting entirely of red-flowering plants. It is difficult to state whether this result indicates a misclassification of the F2 parent or whether some other experimental error was to blame for it. Taken as a whole the data adequately establish the monogenic nature of the pink red character contrast. Light pink is to be considered as incompletely dominant over red, and the genetic difference may be designated by the symbols R for light pink and r for red. The analysis of the leaf-base difference proved to be rather complicated. F1 was petioled, but the petiole was shorter than that of angustifolia and the wing of the petiole was more amply developed. In F2 a hopelessly complex series of forms was obtained ranging from extremely long-petioled to very broadly sessile types. Although it was impossible to demonstrate any valid Mendelian distribution in F2, it was possible to distinguish

certain forms as centers of distribution. Twenty F2 selections with respect to the character of the leaf base were made and their progenies were studied in F, and subsequent generations. The twenty selections fell into six general leaf types, the names and descriptions of which follow:

1. Stenophylla, long-petioled like angustifolia, and with a minimum wing development along the petiole.

2. Latifolia, short but distinctly petioled like the F1, and with a variable wing development.

3. Lanceolata, broad-based sessile leaves with long lanceolate blades. 4. Loriifolia, sessile leaves with very narrow strap-like blades.

5. Auriculata, leaves with the blades sharply constricted at the base, nearly if not quite to the mid-rib, and typically with clasping auricles. In some auriculata forms the auricles may be absent, in which case the leaf may appear to have a short distinct petiole.

6. Sessilifolia, sessile leaves with a broad base and a broad clasping insertion.

Of the above six types of leaves, three, lanceolata, loriifolia, and sessilifolia, differ merely in width of blade. Genetically they appear to be identical in their leaf-base factors. For the purposes of this discussion, therefore, it is only necessary to distinguish four primarily leaf-base types, stenophylla, latifolia, sessilifolia, and auriculata.

As we have stated, F2 gave no decisive evidence either as to the number of factors involved in the leaf-base contrast or as to the interactions among them. In order to obtain suitable analytical material we were obliged to study populations of F3 and subsequent generations. In such populations a notable simplification was observed in the number of segregation products, and the distribution into classes was more distinct. In the course of the investigations, also, constant derivatives of the various leaf-base types mentioned above were established, and further information as to the genetic relation of the different types was obtained by intercrossing these lines and by crossing them with the original parents. Theoretically such lines should differ less from the parents and from one another than the original parents did from each other, and practically this was found to be the case. The behavior in skeleton of selections of various leaf-base types is given below.

Stenophylla selections were observed to segregate in a variety of ways. Two populations bred true for stenophylla; three segregated into 3 stenophylla: 1 sessilifolia; and one gave 3 stenophylla: 1 auriculata. A latifolia derivative crossed with angustifolia gave F1 stenophylla, and F2 3 stenophylla: 1 latifolia.

Latifolia selections proved rather perplexing. In some cases latifolia is evidently a complex hybrid expression, as is evidenced by the fact that the F1 cross between the original parents was typically latifolia in appearOne selection repeated the complex F2 segregation in F3; two bred

ance.

true for the latifolia leaf-base type; one gave a fairly definite segregation into 3 latifolia: 1 sessilifolia with subsequent establishment of both types in constant derivative lines; and one population gave 3 latifolia: 1 sessilifolia.

Sessilifolia selections behaved very simply. Of nine such selections, five bred true for sessilifolia, and the remaining four gave 3 sessilifolia: 1 auriculata.

Auriculata selections appear to breed true whenever tested. One population is an exception to this statement, but it was unfortunately not further investigated. Two other selections bred true for auriculata. An F light pink auriculata derivative crossed with macrophylla (red sessilifolia) gave pink sessilifolia in F1, and 133 pink sessilifolia: 40 pink auriculata: 53 red sessilifolia: 16 red auriculata in F2, a very close approximation to an independent dihybrid expectation.

On the basis of these facts we have been bold enough to offer provisionally the following formulation for the major differences in leaf-base characters: Ss, stenophylla versus sessilifolia, SS is long-petioled like angustifolia, ss broadly sessile like macrophylla. The heterozygote may possibly approach an intermediate condition similar to latifolia.

Ll, stenophylla versus latifolia. SSLL is long-petioled like angustifolia; and SSI, short-petioled like latifolia, and with a distinct but not broad wing on the petiole. Latifolia is evidently a modified petiolate form.

Aa, sessilifolia versus auriculata, ssAA has the broad clasping leaf-base characteristic of macrophylla; and ssaa the deeply constricted leaf-base with flaring auricles of auriculata. Auriculata is clearly a modified sessile form.

As to the completeness of dominance in any of these factor pairs, we can say very little because of the difficulty of evaluating the effect of the residual genotype. Likewise the significance of the wing in latifolia or of the auricles in auriculata is not definitely established on account of the extreme genetic difference which existed between the original parent varieties.

The Calycina-Virginica Series. In the calycina-virginica (Maryland) series most of the attention was given to flower color and flower form. The flower color of calycina was red like that of macrophylla, and that of virginica was light pink like that of angustifolia. The results were in full agreement with those obtained from that series. The F1 was pink and F2 gave 73 pink: 23 red, with the same variation in the pink class as that noted for the preceding series. Five red F2 segregants gave 125 F3 plants all red-flowering. Of twelve F3 families grown from pink segregants, three gave only pink-flowering descendants, and nine exhibited segregation into 3 pink: 1 red, the actual totals being 170 pink: 52 red.

Calycina is characterized by the production of split hose-in-hose flowers. The calyx is strongly developed and petaloid and it is also deciduous in