100 CARNEGIE INSTITUTION OF WASHINGTON. 



the precipitin reaction. Considerable time has been consumed in 

 acquiring proper technic for the preparation of the mold proteins and 

 in overcoming the difficulties due to the fact that the *'press-saft" 

 (expressed juices) which they wished to inject is more or less toxic. 

 However, rabbits were immunized to the plus (+) and minus ( — ) 

 races of two species of mucors. In both cases, the plus (+) "press- 

 saft" when mixed with the plus (+) immune serum gave a stronger 

 precipitate than the minus (— ) ''press-saft" with the plus (+) 

 serum, and vice versa. The difference shows only in the higher dilu- 

 tions, but this is what one would expect upon assumption of the pres- 

 ence of species proteins common to both sexes of a given species in 

 addition to a separate sex protein or proteins — the large amount of 

 precipitate caused by the species proteins making the difference 

 due to the sex proteins. While the results so far obtained will not 

 yet warrant the assertion that Dr. Blakeslee and Dr. Gortner have 

 found a protein responsible for sex, still the tests, in so far as they go, 

 are all consistent with such a conclusion. Furthermore, there is 

 some slight evidence that the same sex proteins occur in different 

 species. This would be a natural inference from the fact that the 

 plus (-I-) races show sexual reaction with minus ( — ) races of other 

 species and vice versa. 



Sex in Lychnis, by George H. Shull. 



In his studies on the heredity of sex in Lychnis Dr. Shull has dis- 

 covered a sex-limited character — the first that has been described for 

 plants. This character is broad-leaf, the determiner for which is, it 

 is concluded, associated with the determiner for femaleness. In 

 making this study 60 pedigreed families of Lychnis were grown to 

 test completely the genotypic character of individuals making up the 

 second generation descended from a cross between a normal broad- 

 leafed female and a narrow-leafed male. The Fj family in question 

 consisted of 32 broad-leafed females, 11 broad-leafed males, and 6 

 narrow-leafed males. The analysis has had the expected result and 

 has shown that there were really four kinds of individuals in the Fg 

 generation, namely, 16 homozygous broad-leafed females, 16 hetero- 

 zygous broad-leafed females, 11 heterozygous broad-leafed males, 

 and 6 homozygous narrow-leafed males. 



These results accord exactly with expectation on the basis of an 

 assumed association of the determiner for broad leaves with the 

 determiner for femaleness and of a double sex- (femaleness) deter- 

 miner in the female and a single one in the male. The result thus 

 serves to confirm Dr. ShuU's conclusions derived from the breeding of 

 hermaphrodites, that the female is homozygous, while the male and 

 also the hermaphrodite are heterozygous for the sex-determiner. 



