334 SYDNEY J. HIOKSON. 



As regards the external features very little can be added to 

 Plate's description. As lie observes, conjugation usually occurs 

 when the gill of the host is unusually crowded with the Dendro- 

 cometes. The two conjugating individuals are in most cases 

 similar in all essential respects. Occasionally, however, a dif- 

 ference may be observed between the two conjugates. Plate 

 states that sometimes one of the individuals which is clearer 

 than the other withdraws its tentacles during the process. Sand 

 (23) says, " Chez Deudrocometes la conjugaison a lieu souvent 

 entre un individu amaigre et un animalcule bien nourri." 

 Mr. Wadsworth and I have frequently observed differences 

 between the conjugating individuals, and Mr. Wadsworth 

 has observed the retraction of the arms of certain individuals 

 during conjugation. 



Plate observed occasionally a conjugation of three indi- 

 viduals. This I am able to confirm, but the occurrence is so 

 rare that no series of nuclear changes in them have been 

 followed. 



As Plate denied the existence of micronuclei, he failed 

 to see any of the stages of their division and conjugation 

 which are described in this paper. In one of his figures 

 he shows the points of the meganuclei in the bases of the 

 conjugative processes, but he did not observe the fusion 

 of these bodies. He gives a good figure to illustrate the 

 fragmentation of the meganucleus at the close of conjugation. 

 In Schneider's (24) figures of Deudrocometes in the act of 

 conjugating the meganuclei are shown to be approaching 

 much more closely than in Plate's figure, and in the same 

 author's figures of the closely allied genus Stylocometes the 

 meganuclei are actually shown to be in contact. The state- 

 ment made by Plate and Schneider that the new meganucleus 

 is formed by a regeneration of the fragments of the old is 

 not correct. 



The mixing of the cytoplasm in the conjugative process is 

 affirmed, and I believe correctly, by Plate, Sand, and others. 

 I have myself observed a fiow of protoplasm passing back- 

 wards and forwards through the membrane with each 



