L - v - HEILBRUNN. 



normal eggs showed the typical zones of centrifuged eggs. The 

 pigment zone extended for about one fourth of the egg diameter 

 along the axis of stratification. The contrast between normal 

 eggs and those which had been treated with the hypertonic 

 solution was very marked. The latter as a rule showed no 

 stratification whatsoever, although some eggs showed just the 

 beginnings of such a process, the pigment granules being slightly 

 more abundant at one pole of the egg than at the pole opposite 

 to it. 



The experiment was repeated on July 24. In this case un- 

 fertilized eggs were subjected to "NaCl hypertonic sea-water" 

 at 10:29 A.M., and about 25 minutes later they were placed 

 into one tube of the centrifuge. Into the other tube, normal 

 eggs were placed. Then (at 10:55^ A.M.) the tubes were 

 revolved for 19 seconds at the rate of 171 revolutions per second. 

 Upon examination, the normal eggs showed complete strati- 

 fication under low power of the microscope. High power examina- 

 tion showed that a few pigment granules had not reached the 

 pigment zone, but had lingered near the equator of the eggs. 

 The eggs treated with hypertonic sea-water showed no strati- 

 fication. In some eggs one pole was slightly paler than the 

 other, and fewer pigment-bearing granules could be found at 

 this pole. But even in these eggs, the pigment was scattered 

 throughout every part of the cytoplasm. At 11:29 the eggs 

 in hypertonic sea-water were centrifuged again and compared 

 with normal eggs given the same treatment. Longer and more 

 vigorous centrifuging was resorted to, and the tubes of the centri- 

 fuge were revolved 186 times per second for 35 seconds. The 

 normal eggs now appeared perfectly stratified; they were often 

 elongated as a result of the treatment. The eggs in hypertonic 

 sea- water usually showed only the beginnings of stratification, 

 a tendency for the pigment to be massed toward one pole. In 

 a few eggs, however, the pigment was practically limited to one 

 half of the egg. 



These experiments show a striking increase in cytoplasmic 

 viscosity after eggs have been exposed to hypertonic solutions. 

 This could be noted both by observation of the flow of the cyto- 

 plasm itself, as well as by more careful observations of the 



