THE CATALYST ENTELECHY IN DIFFERENTIATION 209 



F. E. Lehmann 62 found that trichlorbutyl alcohol, a narcotic which 

 does not inhibit the primary evocator in the dorsal lip of the amphi- 

 bian blastophore, 63 can inhibit the secondary evocators which direct 

 the formation of a lens by an eye-cup. The degree of inhibition, up 

 to complete absence of lens, depends upon the temperature (less at 10° 

 than at 22°), on the narcotic concentration, and also on the stage of 

 development when the narcotic is applied. After the lens-forming 

 ectodermal thickening had appeared, lens formation proceeded despite 

 the narcotic, which seems incapable of interfering with the catalyst 

 system, once this is established. Before this, the narcotic may possibly 

 block off some carrier or prosthetic group. 



Needham points out that "These facts raise the question of the 

 naturally-occurring blindness in cave-dwelling animals. There can 

 be little doubt that it involves a series of effects due to interference 

 with the inductor chain brain— ^eye-cup— >lens-»cornea at various dif- 

 ferent points." 



An eye-cup brought experimentally into contact with undeter- 

 mined ectoderm for 24 hours induces lens formation; and ectoderm, 

 transplanted from a distant region to a place over the eye-cup, devel- 

 oped a lens. But Spemann found that in many amphibia, lens forma- 

 tion can take place without eye-cup assistance; in fact, in the frog 

 Ra?ia fusca and the newt Triton vittatus lens-forming competence is 

 distributed all over the ectoderm. In the toad Bombinator, any part 

 of the head ectoderm will form a lens, but trunk ectoderm will not. 

 In the frog Rana esculenta, only the presumptive lens district showed 

 competence (ability to form a lens following stimulation by the 

 evocator). 



These facts show the danger of framing a theory on the basis 

 of too limited a group of experiments, even within a very re- 

 stricted field. An acceptable theory of life processes must be 

 broad and versatile enough to be consistent with all experiments 

 in any field, no matter how remote from the field in focus. The 

 catalyst theory of life seems to meet this criterion, despite our 

 present inability to unravel the enormous intricacies in a single 

 cell. 



Returning now to the cave-dwelling animals, they and prob- 

 ably also their foods, are protected from direct solar radiation, 

 though possibly more exposed to such telluric radioactive radia- 

 tions as might exist in their habitat. Apart from any effects 

 which might be produced by abnormal or mutant genes, it is well 

 known that eye-cup and other suppressions such as loss of hind 

 limbs may be produced in pigs by restricting the mother's dietary 



