132 



THE PROTOZOA 



by fission or gemmation, as in Foraminifera (p. 235), Arcella 

 (Fig. 80), etc. so-called microgamy, which may be isogamous or 

 slightly anisogamous. In the third case, syngamy is between two- 

 individuals showing the utmost disparity in size, a tiny micro- 

 gamete and a bulky macrogamete, as in Coccidium (Figs. 63, 152) ; 

 the result being am'sogamy of the most pronounced type. 



From these facts, it is abundantly clear that sj^nganiy in the 

 Protista cannot be regarded as related specially to reproduction, 

 but as a process affecting the life-cycle as a whole, related equally 



W5^j<t|^ 



FIG. 71. Copulation of Actinophrys sol. A, Two associated free-swimming 

 individuals. B, The two individuals are beginning to encyst themselves ; their 

 nuclei (N., N.) are preparing for karyokinesis ; an outer gelatinous envelope (g) 

 is secreted round the two gametes, and also round each individual an inner 

 cyst -envelope (c.), incomplete at the surface of contact. C, The nucleus of each 

 gamete is dividing by karyokinesis (first polar spindle, p.sp.). D, Formation 

 of the polar bodies or reduction-nuclei (r.n.) ; the reduced pronuclei (pn.) 

 take a central position in the body of the gamete ; the bodies of the gametes 

 are beginning to fuse. E, The pronuclei are fusing ; the reduction-nuclei have 

 passed through the wall of the inner cyst. F, The synkaryon (sk.) is beginning 

 to divide by karyokinesis ; the degenerating reduction-nuclei have passed out 

 of the inner cyst. N., N., Nuclei of the gametes before reduction. After 

 Schaudinn, magnified about 850. 



to all vital functions of the organism, and therefore only indirectly 

 to reproduction that is to say, only in so far as reproduction may 

 result from renewed and invigorated vitality. This is equally 

 true of the Metazoa, where, however, the life-cycle begins and ends 

 with the production of a complex multicellular body, composed 

 of soma and germen. Hence, in the Metazoa syngamy is brought 

 into relation with the production of a higher individuality, the 

 body, comparable to the whole Protozoan life-cycle, and it is in 

 this sense that the phrase " sexual reproduction " must be under- 



