Proceedings of the Ohio State Aeadeiny of Science 345 



somes are a type of body related to the nucleolus, we may re- 

 gard their presence as influencing nutritive functions and in 

 some such way controlling sex. If the allosomes are not derived 

 from the chromatin network they need not be considered as 

 special bearers of hereditary characters. They may be put in 

 the same category as nucleoli, centrosomes, plastids, etc. Their 

 presence mav have an influence on tlie chromosomes in making 

 latent or setting free certain hereditary peculiarities which con- 

 trol sexual development. We can, with all the evidence so far 

 brought to light, still say that maleness or femaleness is a con- 

 dition and not a simple character. Nevertheless the presence of 

 such bodies is an exceedingly interesting biological fact. 



According to Wilson the known cases of sexual differences 

 of chromosome groups, where allosomes or ''idiochromosomes" 

 are present, fall into five classes as follows : 



1. "Both sexes with the same number of chromosomes, a 

 pair of equal idiochromosomes present in both. No visible differ- 

 ence between the two classes of spermatozoa or between the 

 male and female somatic groups." 



2. "Both sexes and both classes of spermatozoa with the 

 same number of chromosomes ; the male with a pair of unequal 

 idiochromosomes, half the spermatozoa receiving the large one 

 and half the small one." 



3. "The female chromosome group with one more chromo- 

 some than the male. The male with an unpaired idiochromo- 

 some and an odd spermatogonial number, half the spermatozoa 

 receiving the idiochromosome and half being without it." 



4. "Female group (by inference only) with two more 

 chromosomes than the male. In the male a pair of unequal 

 idiochromosomes, half the spermatozoa receiving both these 

 idiochromosomes, and hence two more than the other half." 



5. "Female group with three more chromosomes than the 

 male. Half the spermatozoa receiving tlu-ee more chromosomes 

 than the other half." 



Wilson is very careful to say that the two kinds of sper- 

 matozoa are female — ■ and male-])roducing and not female — ■ 

 or male-determining. 



