74 REMARKS ON CERTAIN [XI. 



origin of the more complex forms of organic life, namely, that, 

 in accordance with the principle of division of labour, the cell- 

 body of the unicellular ancestor divided into two dissimilar 

 halves, which differed from each other both in structure and 

 function. From a single cell which was capable of performing 

 all functions, a group of cells arose and shared the various 

 kinds of work between them. According to my theory, the 

 primitive division produced two kinds of cells, the mortal cells 

 of the body proper (soma) and the immortal germ-cells. Un- 

 doubtedly Professor Vines beheves, as I do, in the principle of 

 division of labour, and in the role which this principle plays in 

 the development of the organic world ; but the division of a 

 unicellular being into somatic and reproductive cells appears to 

 him impossible, and my explanation of the process as due to 

 unequal cell-division does not satisfy him ; he holds that ' it is 

 absurd to say that an immortal substance can be converted into 

 a mortal substance \' 



At first sight indeed this may appear as a great difficulty ; it 

 is in reality, however, caused by a confusion between two dis- 

 tinct ideas, namely, immortality and eternity. The immortalit}' 

 of unicellular beings and of the reproductive cells of multicel- 

 lular organisms is, I believe, a fact which does not admit of dis- 

 pute. As soon as it is once made clear that the fission of a 

 monoplastid is in no way bound up with the death of either 

 half, there can be no further dispute about the unlimited per- 

 sistence of the individual. But this is very far from affirming 

 that such individuals are endowed with eternal life ; on the 

 contrary, we always assume that the organic life on our earth 

 once had a beginning. The conception of eternity involves the 

 past as well as the future, for eternity is without beginning and 

 without end ; but it is obvious that such a conception does not 

 concern us here. Eternity is at best but an artificial idea ; in 

 reality it is no true idea at all, since we cannot conceive it ; it is 

 only the negation of an idea, being in fact the negation of that 

 which passes away. When we begin to discuss eternity, we 

 see that from the point of view of Natural Science, nothing is 

 eternal except the ultimate particles of matter and their forces ; 

 for no one of the thousandfold phenomena and combinations 

 under which matter and force present themselves to us can 

 1 ' Nature,' Oct. 1889, p. 623. 



