IN MODERN SCIENCE. 



79 



embodies a great, and perhaps insoluble, mys- 

 tery, invalidates the whole of Haeckel's reason- 

 ing on the alleged resemblances of different 

 kinds of animals in 'their early stages. 



A second difficulty arises from the fact that 

 the simple embryo- cell of any of the higher 

 animals rapidly produces various kinds of spe- 

 cialized cells different in structure and appear- 

 ance and capable of performing different func- 

 tions, whereas in the lower forms of life such 

 cells may remain simple or may merely produce 

 several similar cells little or not at all differ- 

 entiated. This objection, whenever it occurs, 

 Haeckel endeavors to turn by the assertion 

 that a complex animal is merely an aggregate 

 of independent cells, each of which is a sort of 

 individual. He thus tries to break up the in- 

 tegrity of the complex organism and to reduce 

 it to a mere swarm of monads. He compares 

 the cells of an organism to the " individuals 

 of a savage community," who, at first separate 

 and all alike in their habits and occupations, at 

 length organize themselves into a community 

 and assume different avocations. Single cells, 

 he says, at first were alike, and each performed 

 the same simple offices of all the others. " At 

 a later period isolated cells gathered into com- 



