232 THE DAWN OP LIFE. 



The answer is that the improvement into sucli higher 

 types does not take place by any change of the ele- 

 mentary sarcode, either in those chemical^ mechanical^ 

 or vital properties which we can study, but in the add- 

 ing to it of new structures. In the Sponge, which is 

 perhaps the nearest type of all, we have the movable 

 pulsating cilium and true animal cellular tissue, and 

 along with this the spicular or fibrous skeleton, these 

 structures leading to an entire change in the mode of 

 life and subsistence. In the higher types of animals 

 it is the same. Even in the highest we have white 

 blood- corpuscles and germinal matter, which, in so far 

 as we know^ carry on no higher forms of life than 

 those of an Amoeba ; but they are now made subordi- 

 nate to other kinds of tissue, of great variety and 

 complexity, which never have been observed to arise 

 out of the growth of any Protozoon. There would be 

 only a very few conceivable inferences which the high- 

 est finite intelligence could deduce as to the develop- 

 ment of future and higher animals. He might infer 

 that the foraminiferal sarcode, once introduced, might 

 be the substratum or foundation of other but unknown 

 tissues in the higher animals, and that the Protozoan 

 type might continue to subsist side by side with higher 

 forms of living things as they were successively intro- 

 duced. He might also infer that the elevation of the 

 animal kingdom would take place with reference to 

 those new properties of sensation and voluntary motion 

 in which the humblest animals diverge from the life of 

 the plant. 



