The Spermatogenesis in Pentatoma up to the Formation of the Spermatid. 9 



ToTAMA (NoGAKusHi, '94 a), Bombyx mori : At the proximal end 

 of each of the 4 testicular follicles is a large cell, around which small 

 cells are concentrically arranged. In opposition to Verson he con- 

 siders this to be a follicle cell, not a germ cell, and that it rather 

 corresponds "to the supporting cells of the testes of Vertebrates or 

 the rhachis of the Ascaris egg-string in its function". It also occurs 

 in the ovary. The spermatogonia contain from 26 to 28 chromosomes, 

 which split longitudinally before the formation of the spindle. In the 

 prophase of the 1st spermatocytic mitosis each chromosome is ring 

 shaped, "each ring consisting of four round chromosomes. . . . Norm- 

 ally there are twenty-eight chromosomes although in rare cases we 

 find them to be twenty-six or twenty-seven. They arrange themselves 

 not in two rows, as Henking and Vom Kath state, but in a single 

 row and their division takes place transversely to their longitudinal 

 axis. After this division the daughter cells prepare to divide with 

 no resting stage. In this second division . . . fourteen of the twenty- 

 eight go bodily into one cell and the other fourteen into the 

 other". 



V. LA Valette St. George ('97), Spermatogenesis of Bombyx 

 and Gastropacha. In the testes of the youngest caterpillars there 

 are numerous small spermatogonia, but no cell of Verson. In larvae 

 of from 4—7 mm in length there appears such a large cell, and the 

 latter is probably a metamorphosed spermatogonium. Its nucleus 

 increases in size and becomes irregular in form; its cytoplasm is de- 

 marcated from that of the surrounding spermatogonia. The latter 

 increase mitotically, and are not derived from the cell of Verson. 

 Likewise in the ovogenesis a Verson's cell appears, but its nucleus 

 does not divide and it takes no part in the formation of ovogonia. 

 He considers that the cell of Verson "als Stütz- und Ernährungs- 

 zelle der Spermato- und Oogonien dient und deshalb nicht als Mutter-, 

 sondern als Schwesterzelle der Ursamen- und Ureizellen anzusprechen 

 sei. Vollständig gleichwerthig mit der sogenannten Fusszelle der 

 Spermatogemme der höhern Wirbelthiere ist die VERSON'sche Zelle 

 übrigens nicht. Während jene bestimmt sind, einen Zellhaufen, welcher 

 aus Spermatocyten besteht, . . . schliesslich zu je einem Spermatosom 

 auswachsen, in ihrem Cytoplasma zur Reife zu bringen, tritt die 

 VERSON'sche Zelle in Verbindung mit einer Vorstufe der Spermato- 

 cyten: den Spermatogonien." 



Verson ('89a to '94) finds in the proximal end of the testicles of 

 Bombyx an unusually large spermatogonium, a "Rieseuzelle", by the 



