92 JACQUES LOEB. 



and was possibly reversed while the eggs were in an early stage 

 of development. It seems to the writer impossible to reconcile 

 these observations with the purely morphological views of 

 Brachet or Herlant. 



Brachet (like Herlant) tries to explain the phenomena of 

 artificial parthenogenesis and fertilization without any consider- 

 ation of the striking chemical processes that accompany fertiliz- 

 ation and artificial membrane formation. He reverts to that 

 standpoint of the pure morphologist which Sachs, in his papers on 

 "Matter and Form in Plants" characterized as "empty formal- 

 ism." This standpoint disregards the sources of energy in life 

 phenomena and treats morphological changes as if they required 

 no source of energy. It seems to the writer that the fact of the 

 necessity of oxygen for development, the fact that mere mem- 

 brane formation (both by butyric acid or by a spermatozoon) 

 raises the rate of oxidations 400 or 600 per cent, and the fact that 

 the amount of rise is identical in both cases, are so striking, that 

 these facts cannot be ignored in a theory of the role of membrane 

 formation in the development of the sea urchin egg. The writer 

 has always considered the changes underlying the membrane 

 formation as the essential factor in the initiation of development, 

 while he considered the formation of a fertilization membrane 

 only as a welcome but not essential indicator of the chemical 

 changes in the surface of the egg; a fact which Brachet, on account 

 of his disregard for the chemical processes, has entirely over- 

 looked. Brachet, from his purely morphological standpoint, 

 erroneously assumes or makes it appear as if I considered the 

 formation of a visible membrane as the only and essential act 

 in the initiation of development. 



