GREGARINIDA, KHIZOPODA, 8PONG1DA, AND INFUSORIA. 11 



spends with the latter in composition, but it has that texture and 

 sort of aspect; it is structureless and organless, and without 

 definitely formed parts. Nevertheless, it possesses all the 

 essential properties and characters of vitality ; it is produced 

 from a body like itself; it is capable of assimilating nourish- 

 ment, and of exerting movements. Nay, more, it can produce 

 a shell ; a structure, in many cases, of extraordinary complexity 

 and most singular beauty (Fig. 2, D). 



That this particle of jelly is capable of combining physical 

 forces in such a manner as to give rise to those exquisite and 

 almost mathematically-arranged structures — being itself struc- 

 tureless and without permanent distinction or separation of 

 parts — is, to my mind, a fact of the profoundest significance. 



Though a Rhizopod is not permanently organized, however, 

 it can hardly be said to be devoid of organs ; for the name of 

 the group is derived from the power which these animals possess 

 of throwing out processes of their substance, which are called 

 " pseudopodia," and are sometimes very slender and of great 

 length (Fig. 2, E), sometimes broad and lobe-like (Fig. 2, A). 

 These processes may flow into one another, so as to form a net- 

 work, and they may, commonly, be thrust out from any part 

 of the body and retracted into it again. 



If you watch one of these animals alive, you see it thrusting 

 out, first one and then another of its pseudopodia, exhibiting 

 changes of form comparable to those which the colourless corpus- 

 cles of the human blood present. The movements of these Rhizo- 

 pods are quite of the same character, only they are much more 

 extensive and effect locomotion. The creature also feeds itself 

 by means of its pseudopodia, which attach themselves to nutritive 

 particles, and then draw them into the substance of the body. 

 There is neither ingestive nor egestive aperture, neither special 

 motor nor prehensile organs, but the pseudopodia perform each 

 function as it may be required. 



But here, again, we labour under an imperfection of knowledge. 

 For, although it is quite certain that the Bhizopocla may multiply 

 by division of their substance — in a way somewhat analogous to 

 that which I detailed when speaking of the Gregarinida — yet, as 

 in that case, we have no knowledge of any true sexual process. It 



