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THE AMERICAN NATURALIST [Vol. LIII 



laws in the same measure as causal changes." A com- 

 plete description is the only adequate explanation. Al- 

 though it is impossible to give a complete description of 

 the physical and chemical processes involved in the ir- 

 ritable mechanism, it should be evident that organisms 

 are irritable because they are systems in equilibrium and 

 as such obey the theorem of Le Chatelier. 



II 



When Adams ( '18, p. 474) says, referring to Bancroft's 

 law: "In other words this is a perpetuating tendency, a 

 method of assimilation, of which reproduction may be 

 considered but a special phase," he makes a serious 

 error. That some other principle is involved is hinted 

 at in the following passages (Adams, '18, p. 474, 475) : 



or hasten activity) and do not change its character, but only the intensity 

 of the response (temperature, enzymes, repetition, etc.). By this method 



Thoni.irko in sunniKU-i/.in.o tlie laws ..f " n.'.,uire<l bcliavi.n- or learn- 

 ing"' fonnnlaifs t uo ]nu->. Tlir tirsl is (-M-nlially a slalcment of Ban- 



P.iit whfii Adams ('is, p. 47.")) states: "This law ap- 

 )ifar> 1(1 1)1' a cdrollai'v of liaucroft's law which is con- 

 eeiiu'd with intc-rt\Tence or retardation," he is dodging 

 the question. 



The second principle which Adams calls the law of re- 

 inforcement is the basis of assimilation and the related 

 processes of growth, reproduction and inheritance. That 

 the assimilation of an organism may take place, three 

 conditions are essential: {a) available materials to con- 

 struct the organism; {h) a supply of energ>^; and (c) 

 the presence of the living organism. There are also cer- 

 tain formal conditions of temperature, pressure, etc., 

 which need not concern us at present. In short, assimila- 



