240 From Matter to Man. 



reciprocity which is developed between the primal 

 epiblast and its environments. 



5. Metamorphosis. — An important factor in organic 

 evolution, hitherto minimised, is that common phe- 

 nomenon metamorphosis, characteristic of nearly 

 all organisms in the sub-kingdoms of vegetalia and 

 animalia. In the lowest fungi and algae, a spore 

 passes by " alternation of generation " through several 

 moults before reproducing the parent type. In the 

 protozoa, hydrozoa, actinozoa, and polyzoa, meta- 

 morphosis is general ; the difference in appearance, 

 organisation, and function in all the stages being 

 equally as marked as in man's embryonic transfor- 

 mations. In insects, metamorphosis is universal. 

 Among the crustaceans, the barnacle, acorn-shell, 

 crab, and lobster, evince strange metamorphoses. 

 The tadpole stage of frogs is familiar to all ; while 

 the marsupials among the mammals (kangaroo, 

 opossum, etc.) produce their young imperfectly 

 formed, and nurse them in pouches until fully 

 developed. 



The significant fact for human evolution in con- 

 nection with these metamorphoses is, that reproduc- 

 tion does not occur in any of the intermediate stages, 

 but only in the mature animal. For instance, the 

 butterfly does not reproduce either in the caterpillar 

 or chrysalis state, but only when fully developed as a 

 butterfly. Similarly, in the series of metamorphoses 

 through which all primordial organisms transmuted 

 while developing from the ovule to the mature phase, 



