430 EVENINGS AT THE MICROSCOPE 



Polystomella crispa, a fair sample of its class, and though, 

 not more than one-thirtieth of an inch in diameter, it is 

 a giant compared with the Arcella. 



There is more, however, than the shell to be seen; 

 though so filmy and shadowy that I wonder not at your 

 overlooking it. Extending from two opposite sides of the 

 shell to a distance each way considerably exceeding its 

 diameter, you discern fine threads of clear jelly, running 

 out in long points. The power you employ is not sufficient 

 to enable you to resolve their detail: and for this, I will 

 try to secure a specimen for the microscope. 



In this other live-box, then, I enclose one of the white 

 specks from the moss-like clothing of the stones. It is, 

 I see, of another species, namely, Polymorphine oblong, 

 but it will answer our purpose equally well. 



At present we see only the shell, the removal of the 

 animal having induced it in alarm to withdraw the whole 

 of its softer parts within the protection of its castle. We 

 must have a few minutes' patience. 



Now look again. From the sides of the opaque shell 

 we see protruding tiny points of the clear sarcode; these 

 gradually and slowly so gradually and slowly that the 

 eye cannot recognize the process of extension stretch 

 and extend their lines and films of delicate jelly, till at 

 length they have stretched right across the field of view. 

 The extension is principally in two opposite directions 

 corresponding to the long axis of the shell; though the 

 branched and variously connected films often diverge 

 considerably to either side of these lines, giving to the 

 whole a more or less fan-shaped figure. 



These films are as irregular in their forms and sizes 

 as the expansion of the sarcode of Amoeba, with which 



