THE CATALYST ENTELECHY IN DIFFERENTIATION 



201 



the "raw material" supply and therefore the output of other cata- 

 lysts. 



Selective adsorption, followed by elution, could also establish 

 local concentrations sufficiently large to permit a substance to 

 function in any of the just-mentioned capacities of prosthetic 

 group, carrier, catalyst, elutor, or inhibitor. The work of Sved- 

 berg and his school, above mentioned, adumbrates how profound 

 may be the consequences for catalyst formation or modification. 

 On the other hand substances locally formed may be carried else- 

 where to exert specific effects — the hormones, for example. 



The interplay of these numerous possibilities indicates that in 

 these simple mechanisms the cell has ample scope for the most 

 diverse activities. The potency of local accumulations of trace 

 substances might well be called "trigger action."* The formation 

 of new carriers and prosthetic groups makes possible new enzymic 

 catalysts, which, in turn may direct the formation of still other 

 chemical outputs and structures as the material entelechy devel- 

 ops. 



Sex Determination 



Very slight chemical differences may lead to enormous physio- 

 logical and morphological differences at higher structural levels. 

 Consider the close resemblance of the chief mammalian male and 

 female sex hormones which exert such potent but characteristically 

 different influences. For example, when twin calf embryos are 



0= 



Testosterone 

 (male sex hormone) 



CM! 



Estrone (o? Theelin) 

 (female sex hormone) 



genetically of different sex and the union of the fetal membranes 

 establishes continuous circulation, the sex hormone of the de- 

 veloping bull calf causes the female calf to develop into a free- 

 martin, a sterile intersex with testes and male ducts. 41 Following 



* Iodide therapy may precipitate an attack of acute lead poisoning, by converting 

 lead phosphate stored in the bones into soluble lead iodide. 



