DEATH A PHENOMENON OF ADAPTATION 423 



eludes Herbert Spencer, from whom we have borrowed the above 

 examples, " while, in one sense, the welfare of a species depends 

 on the welfare of its iadividuals, in another sense the welfare of 

 the species is at variance with the welfare of its individuals ; and, 

 further, the sacrifice of individuals may tell in different proportion 

 on the undeveloped and on the mature."^ 



The above considerations lead us to the conclusion that in the 

 whole realm of organic life the individual is secondary to the 

 species, and that the interests of the individual do but serve, 

 in every case, to further the interests of the species to which they 

 are subordinate. Thus, the individual is a function of the species, 

 not an aim in itself. This subordiaation of the iadividual to the 

 whole may be fittingly illustrated by the phenomenon of death. 

 In a previous chapter we spoke of the biological immortality of the 

 Protozoa ; we saw that death, as a phenomenon resulting from 

 a physiological necessity of the organism, is but secondarily 

 superinduced, and that it is by no means inherent to organic life 

 as such, it having first been introduced at a comparatively 

 advanced stage of organic evolution — that is to say, when 

 multicellular beings made their appearance. Death is essentially 

 a phenomenon of adaptation, and a phenomenon of adaptation 

 in the interest of the species at the expense of the individual. 

 In the Protozoa the organism is not sufficiently developed to 

 permit of part of it beiag destroyed and another part of it 

 specialised for the reproduction of the species ; a single cell 

 fulfils all the functions of hfe, both as regards the individual 

 and the race, and its destruction would entail the destruction 

 of the species. In multicellular organisms, however, in accord- 

 ance with the ever-increasing division of physiological labour, 

 which is a phenomenon so universal and constant that we are 

 justified in calling it a fundamental law of organic progress,^ 



1 Spencer, Principles of Sociology, i. 593. Vide also Principlea of 

 Biology, ii., Part VI. 



2 Vide Milne-Edwards, Legons sur la Physiologie et VAnatomie comparees 

 de I'Homme et des Animaux. Paris, Masson, 1857-81. 



