40 HETEROMITA less. 



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 takes in food at ir- 

 regular intervals, and largely intermittent in H?ematococcus, 

 in which the decomposition of carbon dioxide takes place only 

 during daylight, in Heteromita it is continuous, the organism 

 living in a solution of putrefying proteids which it is con- 

 stantly 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,^ the commencement of fission is 

 shown; the anterior flagellum has undergone complete 

 longitudinal division, while the split has extended only about 

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

 B^ the process has gone further, and in b^ 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'— <:*, and is 

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



