dendkocometes paradoxus. boo 



contraction of the vacuole for several hours in one pair, but 

 the period during which this occurs is limited, and during 

 the greater part of the forty-eight or more hours during 

 which the pair remain in conjugation no interchange of 

 particles can be seen. 



An important feature of the conjugation of this genus 

 is that the ordinary vital processes of the individuals are 

 not materially affected during the act. The arms remain 

 fully extended — they catch and swallow particles of food, 

 which are digested in the ordinary course. The contractile 

 vacuoles continue their pulsations for some time after the 

 process has commenced. 



Conjugative Processes. — These processes are formed 

 specially for conjugative purposes in Dendrocometes. In 

 development and in structure they differ from ordinary arms, 

 and I do not consider that they are rightly considered to be 

 homologous with arms. This view does not agree with that 

 expressed by Biitschli (2), who, on the strength of the 

 observations of A. Schneider on Stylocometes, regards them 

 as rudimentary arms. In Stylocometes, according to that 

 author, an arm of each of two neighbouring individuals 

 becomes abnormally thick and elongated to form the conjuga- 

 tive process, and that it is a true arm is proved by the fact 

 that it contains a canal. I have had no opportunity of 

 examining vStylocometes, but I do not feel that Schneider's 

 account of it is convincing. Until his account is confirmed, 

 therefore, 1 must agree with Plate that the conjugative pro- 

 cesses in Dendrocometes are not homologous Avith the arms. 



Biitschli (2) states that in Dendrocometes one individual 

 sends out a process which fuses with the body-wall of 

 another, but that such au occurrence is rare. I have never 

 seen such a phenomenon. In nearly all cases the conjugative 

 processes begin and grow simultaneously, so that they are 

 throughout approximately equal. In the preparation from 

 which fig. 1 was drawn, the individual to the left has a 

 decidedly longer process than the individual on the right, but 

 sucli a difference as this is exceptional. It is impossible to 



