STUDIES IN ARTIFICIAL PARTHENOGENESIS. 

 V. THE ANOMALOUS ACTION OF MERCURIC CHLORIDE. 



L. V. HEILBRUNN, 



UNIVERSITY OF MICHIGAN. 



Traube 1 in 1909 made the claim that substances of low 

 surface tension were more effective in producing parthenogenesis 

 than those of higher surface tension. In 1913 and again in 1915, 

 Heilbrunn 2 proposed a theory of membrane elevation in the 

 sea-urchin egg, according to which the lifting off of the membrane 

 (in this egg) is the direct result of a lowering of its surface tension. 

 If this surface tension theory of membrane elevation is correct, 

 only those substances which cause a decrease in surface tension 

 can produce typical membrane elevation. So far as previous 

 experiments have gone, this is true. There is no case in which 

 membrane elevation has been produced by an agent which does 

 not sharply lower surface tension (Heilbrunn, '24). 



During the past summer an apparent exception was dis- 

 covered. In the course of some work which we were doing with 

 dilute solutions of mercuric chloride in sea-water, my assistant 

 Mr. D. E. S. Brown called my attention to what was apparently 

 true membrane elevation in the egg of the sea-urchin Arbacia. 

 Beautiful wide membranes arose from the egg surface. That 

 these were truly elevated membranes (not swollen membranes) 

 was shown by the fact that they could be made to collapse on 

 the addition of egg albumin to the sea-water. 



The parthenogenetic action of mercuric chloride was known 

 to F. R. Lillie and he mentions it briefly in a paper published in 

 1921 3 (see p. 140). 



It seems certain that mercuric chloride as such could have no 

 great effect on surface tension. Apparently, therefore, the fact 

 that the mercury salt causes membrane elevation can not be 

 made to fit in with the surface tension theory. Because of this 

 apparent conflict, it was thought worth while to further investi- 



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