153 THE MICROSCOPIST. 



CHAPTER XL 



THE MICROSCOPE IN ZOOLOGY. 



WE have already seen that both animal and vegetable 

 structures originate in a jelly-like mass or cell, and that 

 in the simple forms it is difficult, if not impossible, to 

 determine whether the object is an animal or a vegetable. 

 The mode of alimentation, and not structure, is our only 

 guide in the discrimination of the Protozoa or elementary 

 animal forms from Protophytes or simple vegetables. 



It has been proposed by Professor Heeckel to revive the 

 idea of a kingdom of nature intermediate between plants 

 and animals, but it does not appear that any gain to sci- 

 ence would result from such an arrangement. 



I. MONERA. The simplest types of Protozoa are mere 

 particles of living jelly (Plate XII, Fig. 115), yet they 

 possess the power of contraction and extension, and of 

 absorbing alimentary material into their own substance 

 for its nutrition. The Bathybius^ from the "globigerina 

 mud," referred to on page 9d, seems to have been an in- 

 definite expansion of such protoplasm or bioplasm. 



II. RHIZOPODS. This term (meaning root-footed) is ap- 

 plied to such masses of sareode or bioplasm as extend long 

 processes, called pseudopodia, as prehensile or locomotive 

 organs (Plate XII, Fig. 116). The Rhizopods are either 

 indefinitely organized jelly, like Monera, or attain a cov- 

 ering or envelope of membrane called ectosarc, while the 

 thin contents are termed endosarc. The first order of 

 Rhizopods, Reticularia, consist of indefinite extensions of 

 freely branching and mutually coalescing bioplasm. The 

 second order, Radidaria, have rod-like radiating exten- 

 sions of the ectosarc, which do not coalesce. The order 

 Lobosa are lobose extensions of the body itself, as in the 



