40 HETEROMITA 



takes place outside the body so that constructive meta- 

 bolism can begin at once. 



It is worthy of notice that while the process of feeding is 

 strictly intermittent in Amoeba, which only takes in food at 

 intervals, and largely intermittent in Haematococcus, in which 

 the decomposition of carbon dioxide only takes place during 

 daylight, in Heteromita it is continuous, the organism living 

 in a solution of putrefying proteids which it is constantly 

 absorbing. It may be said to live immersed in an immense 

 cauldron of broth which it is for ever imbibing, not by its 

 mouth for it has none, but by the whole surface of its 

 body. 



Respiration and excretion probably take place in the same 

 manner as in Amoeba. It has been shown that the optimum 

 temperature for saprophytic monads is about 18 C, the 

 ultra-maximum or thermal death-point about 60 C. But it 

 is an interesting fact that by very slowly increasing the 

 temperature, Dr. Dallinger was able in the course of several 

 months to accustom some of these forms not Heteromita 

 itself but closely allied genera to live at a temperature 

 exceeding 68 C. 



The ordinary method of reproduction is by simple fission, 

 the process affecting not only the body but the flagella 

 as well. In Fig. 4, B 1 the commencement of fission is 

 shown ; the anterior flagellum has undergone complete 

 longitudinal division, while the split has only extended about 

 a third of the length of the body and ventral flagellum. In 

 B 2 the process has gone further, and in B 3 the products of 

 division are on the point of separating. 



More frequently, however, fission instead of being longitudinal, i.e., 

 in the direction of the long axis of the monad, is transverse, i.e., at 

 right angles to the long axis. This process is shown in c 1 c :! , and is 

 seen to differ from that drsuil>ed in the preceding paragraph in the cir- 



