228 N. M Stevens. 



Anisolabis maritima, a related form, with Miss Randolph ('08) 

 I was interested to see some preparations of Forficula, so I put 

 up a number of testes in Gilson's mercuro-nitric fluid. 



In September and early October I found what appeared to be 

 the same species in Eisenach, GeYmany, and preserved more 

 material. In November some of each set of material was embed- 

 ded, sectioned and stained with thionin, at the Zoologisches In- 

 stitut, Wiirzburg. On examining the preparations with the micro- 

 scope, I was considerably surprised to find a perfectly clear case 

 of an unequal pair of heterochromosomes in the first spermato- 

 cytes, and this is my excuse for adding another paper to the litera- 

 ture on the spermatogenesis of Forficula auricularia. 



In the resting spermatogonia the chromosomes remain con- 

 densed, as figured by Zweiger, and are for the most part in con- 

 tact with the nuclear membrane. Fig. i was drawn by focusing 

 from the surface of the nuclear membrane down to about the cen- 

 ter of the nucleus. In every case where favorable equatorial 

 plates were found the number of chromosomes was 24. Figs. 2 

 and 3 were taken from different sections of the same testis, and 

 Fig. 4 from another individual. Occasionally one finds a sug- 

 gestion of a synizesis stage, but this stage is certainly very incon- 

 spicuous and probably very brief. Fig. 5 shows one such nucleus 

 with one isolated chromosome which corresponds fairly well in 

 size to the larger heterochromosome. There is no evidence as 

 to when synapsis occurs. 



At the beginning of the growth stage of the spermatocytes one 

 finds the chromosomes passing from the concentrated condition 

 of the spermatogonia (Fig. i) through a transition stage (Figs. 6 

 and 7) into a spireme stage (Fig. 8), in which the chromatin thread 

 is slender and pale in both thionin and iron-haematoxylin prepara- 

 tions (Fig. 8). The heterochromosome pair [x) is clearly distin- 

 guishable in these stages, and one, two or more plasmosomes are 

 present {p). 



The spireme soon shortens and thickens (Figs. 9-11) and fre- 

 quently the heterochromosome pair may be seen to be composed 

 of a larger and a smaller chromosome (Figs. 7 and 11). Fig. 12 

 shows other forms which the heterochromosome pair mav assume 



