THE SOUECE OF BOTHRIOCEPHALUS LATUS IN JAPAN, 51 



From what ha.s been said it is appai*ent that the (last) inter- 

 mediate host of B. latus includes several species of fish which may 

 belong to different families and that the principal source of that tape- 

 worm may vary according to localities. 



In Japan, where as already said, B. latus is abundant, none of 

 the above-mentioned fishes are known to occur, although the pike is 

 said to exist in Sasrhalien. What fish is then the source of B. latus 

 in Japan? 



There has Ijeen among the Japanese a popular belief that tape- 

 worms develope from eating certain fishes. Onchorhynchus Perryi 

 Hilgd. (Mas2i) and Onchorhynchus Haberi Hilgd. (^Sake) were the 

 most suspected, a belief which was certainly without any scientific 

 basis. Guided by this suspicion, however, I examined in May 1886 

 a specimen of Onchorhynchus Perryi, and was not disappointed. 

 Seven Bothriocephalus-larva', unmistakeable by the configuration of 

 their head, were found imbedded in the trunk-muscles. In form, size 

 and motions, they corresponded exactly with Braun's description and 

 figures of the larva of B. latus. 



Concerning the appearance of the larvœ I have nothing of impor- 

 tance to add to what is already known. Nevertheless 

 a few words about them mi"ht be useful, since zooloiii- 

 cal Hterature is not accessible to many in Japan. The 

 larva of B. latus is a slender elongated worm of white 

 color. The body is properly speaking not flat but 

 rather thick. Its length varies from 8 to 30 mm, its 

 breadth from 1 to 3 mm. When contracted, the leno'th 

 is reduced by more than one-half, but the ])readth rela- 

 tively increases so that it acquires a thick wrinkled ""^ „ , . 



" A Larv:t of Botunoce- 



form. The head is then involuted and shows a cleft-like onchorhyLchus Per- 



ryi. a, iu contracted; 



depression at the end. If such a larva be put into AbÔut*'2x"maguified." 



