III.] LIFE AND DEATH. I31 



In this remarkable arrangement we cannot discern anjlhing 

 except an evident adaptation of the life of the body-cells to re- 

 productive purposes, and this adaptation was rendered possible 

 because, after the evacuation of the sexual cells, the body ceased 

 to be of any value for the maintenance of the species. 



But even if we assume, that the death of the Orthonectides 

 is, in Gotte's sense, a consequence of reproduction, inasmuch 

 as, in the two forms of females as well as in the male, the ex- 

 trusion of a mass of developed germ-cells or embryos deprives 

 the organism of the physiological possibility of living longer, 

 how can we explain the necessity of death as a direct conse- 

 quence of reproduction in all Polyplastides ? Is the body— the 

 sofna — of the Metazoa so imperfectly developed, as compared 

 with the reproductive cells, that the extrusion of the latter 

 involves the death of the former ? As a matter of fact in the 

 majority of cases the relations are reversed ; the number of 

 body-cells usually exceeds the germ-cells a hundred- or a 

 thousand-fold, and the body is, as regards nutrition, so com- 

 pletely independent of the reproductive cells, that it need not 

 be in the least disadvantageously affected by their extrusion. 

 And if the Orthonectid-like ancestors of the Metazoa were com- 

 pelled to give up their insignificant somatic part after the ex- 

 trusion of their germ-cells, because it could now no longer sup- 

 port itself, does it therefore follow that the somatic cells had 

 for ever lost the power of surviving, even when their phyletic 

 descendants were surrounded by more favourable conditions ? 

 Had they to inherit 'the necessity of death' for all time? 

 Whence came this great change in the nature of organisms 

 which, before the difterentiation of Homoplastids into Hetero- 

 plastids, were endowed with the immortality of unicellular 

 beings ? 



And it must be remembered that it is only an assumption 

 which places the Orthonectides among the lowest Metazoa 

 (Heteroplastids). I do not intend to greatly emphasize this 

 point, but the formation of the Gastrula by embole and the 

 absence of a mouth and alimentary canal show that these 

 parasites are extremely degenerate, and the same may be said 

 of almost all endoparasites. The Gastrula, as an independent 

 organism, was without doubt primitively provided with both 

 mouth and stomach, and the mass of ova filling the female 



K 2 



