22 Henriksen, A Functional vicw of Development. 



emphasize that all we can say is that A gives rise B and B to C 

 and the adaptation of A may give rise to a large and a small B. 



Neither should we forget that each part becomes differentiated 

 by different kinds of nourishment, and if this is absent it cannot 

 differentiate in a manner natural to its kind in order to develop 

 bone, for ex. The chemical elements present in the bone must be 

 taken in as food. 



If the earlier blastomeres are separated the nnmediately tend 

 to do away with the relations established when they were destined 

 to become merely a part of an organism, and tend toward estab- 

 lishing the relations necessary to produce the equilibrinm of the 

 species. This is not alone true of first cleavage, but it has been 

 shöwn by Watarge that in some forms even one blastomere of the 

 sixteen-cell stage may form a complete larva of but one sixteenth 

 the size of the normal larva and one half blastomere forms a larva 

 of but half the size of the normal one. This illustrates very clearly that 

 nuiside of those factors already mentioned we have one factor common 

 to all organism, nainely that each one possesses only so much 

 growth energy as is necessary to produce a normally developed 

 individual, and as this energy is divided into various parts, we find 

 a corresponding decrease in size of the larva. We should also be 

 aware of the fact that where we have unequal division as to size 

 of the cells, as in the formation of micromeres, we find a corre- 

 sponding relation in the division of this common factor, growth 

 energy, as has been shown by isolating them and the resulting 

 larvae have been of corresponding size. So we find ad least that 

 the amount of substance present seems to correspond to the 

 amount of growht energy within the species. 



If we then take the normal development of one of these forms 

 we find that each blastomere, for ex. forms a definite part of the 

 embryo as the study of cell linages has brought out very distinctly, 

 but if they are separated each one will form a dwarf larva. There- 

 fore in such a case, we can no more say that the egg is a micro- 

 cosm of the adult than to take Darwiifs illustration, where he 

 shows that the humble-bees are indispensible to the pollination 

 of the heartsease {Viola tricolar) and the red clover {Trifolium 

 repens), as no other bees can reach the neetar of these flowers. 

 So if the humble bee became extinet or very rare in England the 

 heartsease and the red clover would become rare or wholly 

 disappear. The number of humble bees depends on the number 

 of field mice which destroys their comb and nests and the number 

 of mice depends on the number of cats to destroy the mice, and 

 still more we could add Prof. Huxley's sarcastic remark that the 

 number of cats depend on the number of old maids and thus to 

 a great extent the welfare of the English people depend on the 

 number of old maids found in England. This is the conclusion 

 drawn by studying a series of relations but no one would dare 

 to say tliat in the cats we must have some kind of a microcosm 

 of the clover and heartsease, although the number of these are 



