2 7 6 



CHAPTERS ON EVOLUTION. 



rim or margin of the body forms a covering. Then this globular 

 body-margin ruptures ; the little spindles of protoplasm escape there- 

 from ; and finally each develops, with but little further change, into 

 a gregarina like that from which it was derived. 



Now, such a life-history as this is instructive, especially when 

 viewed from the stand-point of animal individuality. The single 

 gregarina is seen to break up into numerous other gregarinae, each 

 of which repeats at first the single state, and then the process of 



division into particles 

 which characterised its 

 parent. Each gregarina, 

 then, may, in natural-his- 

 tory language, be named a 

 "persona," or "person" 

 that is to say, it is a single 

 or " individual " animal ; 

 representing in itself, even 

 as does each of the higher 

 animals, a defined and 

 component element of the 

 animal world. A like re- 

 mark might be made of 

 many other lower forms 

 of animal life. An Amoeba 

 (Fig. 184), which differs 

 from a gregarina chiefly in 

 that it possesses an active 

 power of locomotion by 

 pushing out its body sub- 

 stance into long processes 

 (Fig. 184), is likewise a 

 single " individual " animal, which represents, as an oyster or a bird 

 does, a well-defined unit quantity in the sum total of the living series. 

 There is, however, one important epoch in the life of both gregarina 

 and amoeba, when each organism for both exhibit essentially the same 

 course of development shows a tendency to lose its individuality in 

 the division of its body to form other individuals. At one stage in its 

 development, namely, when filled with the miniature " spindles " or 

 protoplasmic particles (Fig. 183,0) into which it has divided itself, the 

 gregarina or amoeba in reality becomes a colony or aggregation of beings. 

 But such a tendency is at the most transitory, and the temporary colony 

 speedily resolves itself into a diffused and separated mass of young 

 organisms, whose individuality, and indeed whose whole existence, 

 is due to the destruction of those of their parent. In another sense, 

 the amoeba may occasionally show this tendency to lose its single 



FIG. 184.- DIFFERENT FORMS OF AMCEB.E. 



