5o8 Alice M. Boring 



Chlorotettrix unicolor, 1 1 chromosomes 



Chlorotettrix vividus, 9 chromosomes 



Aphrophora quadrangularis, 11 or 12 chromosomes 

 Aphrophora 4-notata, 14 chromosomes 



Poeciloptera septentrionahs, 14 chromosomes 

 Pceciloptera bivittata, 13 chromosomes 



8 The number of chromosomes is constant for each species. 

 In the case of Aphrophora quadrangularis, where there have been 

 found both 11 and 12 chromosomes, probably two species are pres- 

 ent, which have not been separated in classification. 



9 The only points in the spermatogenesis in which all of the 

 species of one family resemble each other more closely than they 

 do the species of the other families are the appearance of some of 

 the growth stages and the transformation of the spermatid into 

 the spermatozoon. 



10 In fourteen of the species studied, the individuality of cer- 

 tain chromosomes can be traced from the spermatogonium to the 

 second spermatocyte, a pair of similar chromosomes in the sperma- 

 togonium bearing the same size relation to the other chromosomes 

 of the equatorial plate as a single chromosome bears to the others 

 in the first and second spermatocyte plates. In all the species, 

 the odd chromosome can be traced as keeping its individuality 

 from the growth period to the anaphase of the first spermatocyte 

 division, in Chlorotettrix and Vanduzea arcuata to the metaphase 

 of the second spermatocyte division, and in Enchenopa binotata, 

 from the spermatogonial plate to the telophase of the second sper- 

 matocyte division. 



11 In all 22 species, there is a dimorphism of the spermatozoa, 

 which probably corresponds to the natural dimorphism of sex. 



12 Two species of Fulgoridae in which the female somatic num- 

 ber of chromosomes is 28, while the spermatogonial number is 27, 

 furnish further proof for the theory of sex determination advanced 

 by McClung, Wilson and Stevens. 



Bryn Mawr College 

 May 4, 1907 



