GERM CELLS OF GRYLLOTALPA 291 



somes (fig. 2, A, B) and some 11 (fig. 2, C, D). In the 12-class 

 a small chromosome is never present, while it is always present 

 in the 11-class. All of the chromosomes divide in this division 

 (fig. 2, E, F, G, H, four drawings taken at different levels in 

 the same cell). Hence two classes of spermatozoa are produced, 

 differing as do the secondary spermatocytes. One receives 10 

 autosomes, a single chromosome and the large end of the unequal 

 pair; the other receives ten autosomes and the small end of the 

 unequal pair. The counts in the oogonial and spermatogonial 



•V, 9 *J* •- *•- 

 •** IV Ki v^ 



D 



# # E •*•# F .v.^ *« H %V#| 



Text fig. 2 Gryllotalpa borealis. A, B, C, D, second spermatocyte divisions. 

 A and B the 12-chromosome class; C and D the 11-chromosome class; E, F, G, H, 

 four figures of an early anaphase of a 12-chromosome, secondary spermatocyte, 

 drawn at different levels in the same cell; 1, anaphase of the second spermatocyte 

 division, showing the further separation of the two parts of the single unpaired 

 chromosome. 



divisions also confirm this method of distribution, as there are 

 24 chromosomes in the female and 23 in the male. The male 

 group always has the small chromosome, while the female group 

 does not. This indicates that maturation in the egg is regular 

 and that each mature egg receives 12 chromosomes. When the 

 12-chromosome class of spermatozoa fertilizes an egg, an indi- 

 vidual with 24 chromosomes is produced, a female. When the 

 11-chromosome class meets the egg, an individual with 23 chromo- 

 somes is produced, a male. I wish to emphasize these facts, as 

 some readers may be skeptical as to whether the chromosomes 

 are always distributed as described. This skepticism may have 



