520 



ON THE PROPERTIEE OF COCOONS. 



These figures show that the larger the cocoons are the larger 

 quantity of raw silk they furnish, and vice versa. The O-setsu, 

 however, whose cocoons are of a nearly equal size to those of 

 Akabiki, furnish an exceptionally small quantity of silk. 



As I have stated before, the aboriginal races of silkworms, 

 count a few hundreds, but the more widely distributed and culti- 

 vated races are, so far I have examined, not more than eight. It 

 will not be entirely useless to compare the properties (diameter, 

 tenacity, and ductility) of these eight races with those of some 

 foreign races mentioned in the report of the Laboratoire de la ver 



soie in Lyon. The comparison of the filaments is as 



follows : — 



Races 



meter 



Tenacity 



Ductility 



Akabiki. 



30.4 li 



1 1.8 grams 



13-2% 



Awobiki. 



29.1 



8.1 





Onichijira. 



27-2 



9-8 „ 



12.3 



Koishimaru. 



25.8 ,, 



9-2 



12.5 



Matamukashi. 





8.2 



1 1.6 ,, 



Kimayu. 



28.7,, 



9-1 



12.2 ,, 



Kumako, (second breed.) 



257 



6.3 



9.8 



Natsuko, ( ,, ,, ) 



26.1 ,, 



7-0 „ 



10.9 ,, 



Yellow, (French race) 



29.6 ,, 



9-4 



12.1 ,, 



,, (Italian race) 



30.8 ,, 



97 



13-6 



,, (Chinese race) 



26.3 



7.2 ,, 



9-5 



White, (French race) 



30.5 M 



8.5 „ 



11.2 ., 



(Italian race) 



30.2 



8.8 ,, 



12.8 ,, 



,, (Chinese race) 



25.9.. 



7-5 



10.6 ,, 



This table shows us that the filament of the cocoons of our aborigi- 

 nal races is not thicker than that of the European races ; and the 

 Chinese races which are regarded as giving finer filaments do not 

 show any difference on this point when compared with Koishimaru, 

 Matamukashi, etc. ; and only a few bivoltin races, such as Kumako 

 and Natsuko, produce filaments of inferior quality. 



In conclusion, I do not hesitate to say that our races of silk- 

 worms afford filaments equal in quality to those of any other race ; 

 and the fact that some of our filament are of an inferior quality 

 seems to be due mainly to reeling, an incomplete selection of 

 cocoons, and some other causes. 



I must here express my hearty thanks to Prof Sasaki, under 

 whose direction tin's investigation has been carried out. 



