426 E. I. WERBER 



or 35 cc. or 40 cc.) of a gram-molecular solution (in distilled 

 water) of acetone, only a very few resulting from the employ- 

 ment of butyric acid. Considering the molecular weights of 

 sea-water on the one hand and of acetone on the other hand, it 

 is at once evident that by the addition of the acetone solution 

 to sea-water the latter was quite appreciably diluted. In 

 other words, as far at least as this physical condition is concerned, 

 our experiments with acetone are in principle similar to the 

 experiments performed by Loeb (I.e.) on sea-urchin eggs by 

 diluting the sea-water with fresh water. In both instances the 

 osmotic pressure of the medium surrounding the eggs was low- 

 ered, although less so in my experiments than in those of Loeb. 

 Since, in this way, the difference between the internal osmotic 

 pressure (of the eggs) and the external osmotic pressure (of 

 the surrounding medium) was modified in experiments which 

 besides other monsters yielded a certain number of duplicities, 

 there is no apparent reason to doubt that the origin of the 

 latter is directly traceable to this modification. 



It might perhaps be wondered why relatively few double 

 embryos have resulted from the above described treatment of 

 the eggs. This, however, can, at least partly, be accounted 

 for. The egg of Fundulus heteroclitus, well known for its hard- 

 iness, 17 is relatively little susceptible to physical insults, and it 

 is possible that the dilution of sea-water by the addition to it 

 of such quantities of acetone as I have employed, is not sufficient 

 to cause osmotic blastolysis ('blastotomy' — Bataillon, I.e.) 

 except in a very few eggs. Greater dilution of the sea-water 

 by the addition of quantities of acetone greater than those em- 

 ployed in these experiments is, however, impracticable, for, in 

 that case the degree of chemical action would be higher, and 

 owing to it the mortality would, according to my experience, 

 increase greatly and the few surviving eggs, having sustained 

 so much chemical alteration, would result only in dwarfed, 

 shapeless embryonic masses and fragments. The paucity of 



17 In a number of experiments performed in 1915 in which eggs of Fundulus 

 heteroclitus were subjected to a strong centrifugal force, no alteration of de- 

 velopment or any injury resulted. 



