SPERMATOGENESIS OF SILKWORM. 



219 



By comparing various characteristics of the wild and domesticated 

 silkworms, Sasaki ('98 / came to the conclusion that the former should be 

 taken for the ancestral form, from which the various races of the ordinary 

 silkworm were derived. If so, in the course of domestication the wild 

 form must have acquired two additional chromosomes. But when and 

 how these two came into existence is still an open question. Not unlikely 

 ancient people took hold of a mutant from the wild Theophila and 

 succeeded in producing from it the races better fitted for their need. 



It will be of great interest to study the chromosome groups in 

 the cross of the wild and domesticated silkworms. Male Theophila is 

 known to come sometimes from the mulberry bush to mate with female 

 Bombyx moth and, as I was told, the rearing of the cross is not 

 a difficult task. It is highly probable that in the germ cells of the 

 cross, one chromosome of the domesticated silkworm will not find its 

 mate at synapsis and will appear as an accessory or heterotropic 

 chromosome. 



Zoological Institute, Tokyo Imp. Univ. 

 Nov. I, 19 12. 



Literature. 



COOK, M. H., 'io., — Spermatogenesis in Lepidoptera : Proceed. Acad. 



Nat. Sc. Philadelphia, LXII. 

 Dederer, P. H., '07. — Spermatogenesis in Philosamia cynthia. Biol. 



Bull. XIII. 



HENNEGUY, L. F., '98. — Sur les rapports des cils vibratiles avec les 

 centrosomes. Arch. anat. mie. 1. 



LaValette St. George, '97. — Zur Samen- und Eibildung bei Seiden- 

 spinnen {Bombyx mori). Arch. mikr. Anat. L. 



Meves, F., '97. —Uber den Centraikörper in männlichen geschlechts- 

 zellen von Schmetterlingen. Anat. Anz. XIV. 



Meves, F., '03. — Uber oligopyrene und apyrene Spermien und über 



