ON A NEW CESTODE LARVA PARASTIC IN MAN. 7 



contracted condition. So likewise with all the worms which I 

 have thrown into the cold (summer temperature) physiological 

 fluid. However, for some time afterwards, motion could be restored 

 by imparting a little warmth to the medium they were in. With 

 such worms as I had kept in the physiological fluid, after about 

 four hours had elapsed, my attempt at reviving them into motion 

 was only partially successful ; many of them then seemed to be 

 nearly or quite dead, showing on the surftxce pustule-like swellings 

 due to imbibition of the fluid into the parenchyma. 



Observing the moving worms under the microscope, the nar- 

 rower end of the body — undoubtedly the head — showed most 

 motion. This consisted chiefly in evagination and invagination 

 of the extreme end as well as in a shortening and lengthening 

 of the parts. In the more active individuals the head-end was 

 seen now and then to evaginate and elongate to the fullest extent, 

 exposing the rounded extreme tip of the head (as in fig. 18). At 

 other times there was perceivable on the tip a small depression 

 or concavity, which, especially when the terminal parts of the 

 head was somewhat broadened after a narrow neck-like part as 

 was frequently the case for the time being, reminded me of tlie 

 single terminal sucker known from the fish Bothriocephalid Oy- 

 athocephalus Kessl. But that depression was evidently simply 

 due to invagination of the extremity of the head, for I have 

 frequently seen it gradually but totally disappear as the head-end 

 prolonged itself into a simple finger-like shape, losing the termijial 

 broadening which might be observed so long as the invagination 

 was present. The completely everted, slender head-end moved 

 about as if feeling for something and at the same time generally 

 started a rather lively peristaltic motion which traveled back- 

 wards for some distance. Altogether the movements are such 



