STUDIES IN ARTIFICIAL PARTHENOGENESIS. 357 



Dibasic acids, such as oxalic, succinic, and tartaric, do not lower 

 surface tension nearly so much 1 and they have comparatively 

 little effect upon sea-urchin eggs. Hydroxi-acids act in a fashion 

 similar to the dibasic acids. Finally, hydrochloric and nitric 

 acids have been found to be least effective. 2 These acids lower 

 the surface tension but slightly, as has been shown, for example, 

 by Rontgen and Schneider. 3 Loeb 4 could obtain no results 

 with sulphuric acid, and it is interesting to note that this acid 

 does not produce a lowering of surface tension when dilute. 

 The question arises as to the reason that a return to sea-water 

 is necessary in the case of the above mentioned acids. This 

 point will be made clear later. 



I have now shown that every known method of producing 

 membrane elevation results in a lowering of surface tension. I 

 also found that a number of hitherto untried substances which 

 lower surface tension, can also be used to produce membrane 

 elevation. 



Acetone. According to von Knaffl-Lenz's view that it is the 

 liquefaction of lecithin w r hich causes membrane elevation (see p. 

 8, 1. 12), acetone should be entirely ineffective, as it is well known 

 for its power of precipitating lecithin. On the contrary, I found 

 acetone a very convenient means of producing membrane eleva- 

 tion. Eggs placed in a solution of 3 or 4 c.c. acetone + 25 c.c. 

 of sea-water push out membranes, and cytolysis follows. A 

 very rapid action results if the eggs are placed in more concen- 

 trated solutions of acetone. 5 This can be observed by dropping 

 some eggs into a drop of acetone under the microscope. 



Chloretone. 6 This substance is very effective in producing a 

 lowering of surface tension. I found that a o.i per cent, solu- 



1 J. Trauhe, Liebig's Anr.alen, CCLXV., 27. 



2 In 1905, Loeb (Univ. Cal. Publ. Physiology, II., 113) obtained "practically 

 negative" results on adding these acids to sea-water. In 1909 (Biochem. Zeitsch., 

 XV., 254), he made up his solution in M/2 NaCl, which in itself has been shown 

 to cause membrane elevation, and in this way he met with occasional success. 



3 Loc. cit. 



4 Loeb, "Chemische Entwicklungserregung," p. 105. 



5 Solutions of acetone in sea-water are not as concentrated as they seem, for 

 the acetone tends to be salted out of solution. (See Bernthsen, "Organische 

 Chemie," p. 170.) The surface tension of acetone at 16.8 is 23.35 dynes per 

 centimeter. 



6 Chloretone is a trade name for tri-chlor tertiary butyl alcohol. 



