THE FLAGELLATE INFUSORIA. 



33 



The first sign of fission is a bulging out of the collar, 

 which becomes still more bell-shaped. The flagellum next 

 disappears. Then marks of self-division appear in a nar- 

 row, slight furrow (Fig. -^4:7, B, e), extending from the front 

 half way back along the middle of the body. Meanwhile 

 the collar, which had become conical, expands, and, most 

 striking change of all, two new flagella appear. Then the 

 collar splits into two (Fig?-17, 0), and soon the two new Oodo- 

 sigffl become perfected, when they split asunder, and become 

 like the original Codosiga. Such is the nsual mode of mul- 

 tiplication of the species in the monads. 



A few monads have been observed to become encysted, and 

 to break up into excessively minute bodies, from which new 

 monads have grown. Two 

 individuals of the same form 

 (Heteromita) in certain stages 

 fasten themselves together, 

 the larger absorbing the 

 smaller as if conjugating, 

 like Desmids, the compound 

 body resulting becoming en- 

 cysted ; finally the contents 

 of the cyst become divided 

 into €rither large or minute 

 germs {zoospores) which as- 

 sume the parent form. The researches of Messrs. Dallinger 

 and Drysdale on this Heteromita have proved that while 

 the mature forms may be destroyed at a temperature of 

 61° — 80° 0., the motile germs, with a diameter of ^oaoad 

 of an inch, may be heated to 148° C, without perishing. 



Nodiluca (Fig. 22) has been proved by Cienkowski to be 

 an enormous monad. It is a highly phosphorescent organ- 

 ism, so small as scarcely to be seen with the naked eye, be- 

 ing from ^ to 1 mm. (-01 to -04 inch) in diameter. It occurs 

 in great numbers on the surface of the sea. It has a nearly 

 spherical jelly-like body, with a groove on one side from 

 which issues a curved filament, used in locomotion. Near 

 the base of this filament is the mouth, having on one side a 

 tooth-like projection. Connecting with the mouth is an oes- 



22. — Nodiluca miliaris, after Hux- 

 ley, and its zoospores, s, ptyle ; n, nucle- 

 Greatly magnified. — After Cienkowski. 



