52 I. IJIMA 



luke-warm water or salt-solution, it begins to move energetically. 

 The head is alternately thrown in and out, the body at the same time 

 bending and stretching and exhibiting also peristaltic motions which 

 travel from end to end. The head, when extended, is club-shaped, 

 hardly 1 mm in length and bears two shallow longitudinal grooves, 

 thus essentially agreeing in form with the head of the fully grown 

 Bothriocephalus latus. The body is solid as in the mature w^orm 

 but without any trace of strobilization or of sexual organs. Ex- 

 amined under the microscope, it clearly shows some of the excretory 

 vessels and calcareous bodies, of which there are comparatively many. 

 The larva, as it lies in the flesh, is tolerably extended but with the 

 head always drawn in. It rarely lies straight but usually irregularly 

 coiled. No sort of capsular membrane invests it. Within the body 

 of the host, it by no means makes such active movements as described 

 above ; but it is exceedingly probable that it may at any time shift 

 its position within the host. At least, there can be no doubt about 

 this much, that the larvœ found in various parts of fishes have wan- 

 dered in from the intestinal canal. Braun found them not only in 

 the muscles of the pike, but also in the various organs of its body- 

 cavity, some hanging on the intestinal wall, others free in that cavity. 

 Moreover he found on the liver-surface tracks of their wanderings. 

 In Onchorhynchus Perryi, I have as yet never found them in any 

 other place than in the trunk-muscles. 



To prove that the Bothriocephalus larvae obtained from Oncho- 

 rhynchus Perryi belonged to B. latus, it was necessary to experiment 

 with them. So I swallowed two larvae, one of which was however 

 injured :and my assistant, Mr. M. Kikuchi, kindly offered his services 

 and swallowed three. This was done on May 10*^^ 1886. 



From the 2^^ or the 3^'^^ day, I began to experience now and then 

 slight pains in the duodenal region. This lasted for some days and 



