J- PAUL VISSCHER. 



and thus prevents a second attack. If it is attacked a second time, 

 the result is extensive disintegration of the protoplasm around the 

 point of contact (Fig. 6, C, w). If this point is located at one 

 end of the spirostomum, the opposite end swims rapidly away, 

 leaving behind a trail of disintegrating protoplasm (Fig. 6, E-G). 

 When any part of the protoplasm of this organism begins to dis- 

 integrate, the cytolysis, once begun, progresses rather rapidly until 

 the whole organism has disintegrated. This effect is in contrast 

 with that obtained in Stcntor, in which an attack produced only 

 local and partial disintegration. Apparently the protoplasm of 

 Spirostomum does not possess the power of gelation as observed 

 in Stentor, and thus the cytolytic action continues until the organ- 

 ism is disintegrated (Fig. 6, G). 



The results obtained in numerous other observations made on 

 various other organisms are all in harmony with those which have 

 been described. All these observations seem to show conclusively 

 that the trichocysts discharged by Dilcptus gigas, first temporarily 

 paralyze the prey, then produce a period of increased activity in 

 the nature of a negative reaction on the part of the prey, and 

 simultaneously effect a cytolytic action at the point of contact. 



B. OBSERVATIONS ON THE STRUCTURE OF THE TRICHOCYSTS OF 



Dileptus. 



Numerous specimens of Dilcptus were fixed during various 

 stages in the process of feeding and many different methods of 

 fixation and subsequently staining were employed in an attempt to 

 ascertain the structure of the trichocysts. Before they are dis- 

 charged the trichocysts can be clearly seen in all properly stained 

 specimens (Fig. /). They are found, as previously stated, in a 

 band on the oral surface of the proboscis. When stained they 

 appear as elongated bodies (Fig. 7, t), which do not show any 

 definite internal morphological structure, but appear to be more or 

 less granular, and if stained at all, are always stained deeply. Fig. 

 7 shows the relative number, size, and shape of the trichocysts as 

 seen in 4 p. sections (A-D}, and in a total mount (). In favor- 

 able specimens they can be seen in the living animal, where they 

 appear as colorless, rather transparent bodies which change shape 

 as the animal twists and turns. They have been seen to become 



