VLA SMODROMA TA 



297 



Species. — Before commencing the systematic description of the 

 Protozoa it may perhaps be as Well to remind the reader that in 

 the higher animals the distinctness of a species depends upon the 

 fertility of its members inter se, but not usually with members of 

 other species. 



In protozoology and bacteriology many mere varieties have been 

 called species, but such variants lack any morphologically specific 

 character, and are merely separated from one another by physio- 

 logical characters, which, as we have seen in the section on evolution 

 of disease, can be made to alter by change of environment. 



It is convenient and useful for purposes of identification and 

 reference to give them names as though they were true species, 

 and this does no harm so long as the reader does not expect to 

 find morphologically specific differences in these forms, which can 

 only be separated biologically and physiologically. 



DIVISION A: PLASMODROMATA Doflein, 1901. 

 Synonym— Cytomorpha Hatschek, 1888. 



Definition. — Protozoa in which the nucleus is not separated into 

 reproductive (micronucleus) and non-reproductive (macronucleus) 

 portions. 



Classification. — The Plasmodromata may be divided into phyla 

 according to the following scheme 



{a) With motile organs in adult stage 



I. Move and capture food by pseudopodia — Sarcodina. 

 II. Move and capture food by flagella — Mastigophora. 

 (5) Without motile organs in adult stage 



I. Spore formation distinct from and takes place after 

 the trophic phsise—Teleosporidia. 

 II. Spore formation and trophic stage proceed simul- 

 taneously — Neosp oridia . 



PHYLUM: SARCODINA Hertwig and Lesser, 1874. 



Definition. — Plasmodromata which move and capture their food 

 by means of pseudopodia. 

 Classification. — The Sarcodina may be classified as follows: — 



{a) Without axial filaments in the lobose, filose, or reticulose 



pseudopodia — Rhizopoda. 

 (b) With central axial filaments in fine ray-like pseudopodia — 



Heliozoa Haeckel, 1866; Radiolaria Haeckel, 1861. 

 Remarks. — -Only the Rhizopoda concern us at present. 



CLASS: RHIZOPODA von Siebold, 1845. 

 Definition. — -Sarcodina, parasitic or free-living, without axial 

 filaments in their lobose, filose, or reticulose pseudopodia. 



