DEPARTMENT OF EXPERIMENTAL EVOLUTION. 101 



One result expected by Dr. Shull has failed of realization, so that a 

 perplexing situation has been created which, however, in no wise 

 invalidates the conclusions to be derived from the facts given above. 

 It was predicted that in the crosses between heterozygous females and 

 narrow-leafed males there would appear a new type — narrow-leafed 

 females. This prediction has not been fulfilled. Although in the 

 past Dr. Shull's cultures of Lychnis have contained an average of 

 about 62 per cent females, the 37 matings between broad-leafed females 

 and narrow-leafed males whose offspring have been grown this year 

 have produced only 14 females in nearly 2,700 individuals, or a little 

 over 0.5 per cent. Eight of these females occurred in a single 

 family in which no narrow-leafed plants were to be expected, because 

 the mother was homozygous for broad leaves. Only two females 

 occurred in families which also contained narrow-leafed plants, and 

 these two chanced to be broad-leafed. One narrow-leafed female did 

 appear, but in a family in which it was not due theoretically to appear. 

 This plant differed so profoundly from all his other specimens of 

 Lychnis that it is considered likely that it will be found to be a mutant 

 of an interesting nature. To offset the 31 families in which not a 

 single female occurred, in four families there was not a single male 

 or hermaphrodite. Three of these families were the total progeny 

 of a single hermaphrodite crossed upon three unrelated females. 



A mating between a heterozygous, broad (narrow) female and an 

 unrelated broad-leafed hermaphrodite has produced a progeny con- 

 sisting of 67 broad-leafed females, 15 broad-leafed hermaphrodites, 

 and 9 narrow-leafed hermaphrodites, showing that this unrelated 

 hermaphi'odite parent was a heterozygote in the broad-leaf character — 

 an independent origin of this interesting mutation. The males of any 

 race of Lychnis might have the broad-leaf determiner lost from the 

 male determiner, and such a condition could be discovered only when 

 a female is found in which there has been a similar mutation in a female 

 determiner. Appreciating the importance of this possibility in inter- 

 preting the origin of the first narrow-leafed male. Dr. Shull has made 

 crosses between the males of all his independent races of Lychnis and 

 heterozygous females to ascertain how generally the determiner for 

 maleness is lacking the broad-leaf determiner. 



Dependence of Secondary Sex-Characters on the Germ-gland in Poultry, 

 by H. D. Goodale. 



Dr. Goodale continued the work described in the last Year Book, 

 page 87, both at this Station and at Amherst. Castrated drakes do not 

 assume the summer plumage. All males which assumed the summer 

 plumage, although previously castrated, have been dissected and, in 

 each case, a greater or less amount of testicular material has been found. 

 It has not been deemed desirable, at the present, to kill those which 



