198 L. V. HEILBRUNN. 



mersed in 25 c.c. of 0.55 M NaCl at 10:58 A.M. Beginning at 

 11:165 A.M., the eggs were centrifuged for 17 seconds at the 

 rate of 153 revolutions per second. When examined, the eggs 

 in NaCl alone showed stratification, although the boundary 

 between the various zones was not a sharp one. Gray cap, 

 hyaline zone, granular zone, were distinguishable, but the pig- 

 ment was not entirely restricted to^the pigment zone. On the 

 other hand, the eggs in the alkaline NaCl solution showed not 

 a vestige of stratification, in every case the pigment-bearing 

 granules were evenly distributed throughout the cell. In these 

 eggs exposed to an alkaline NaCl solution, membrane swelling 

 had taken place. Similarly when membrane swelling was in- 

 duced by i per cent, albumen, coagulation followed the endos- 

 mosis thus produced. On August 4, 1914, at 10:40 A.M., some 

 eggs were placed in a filtered I per cent, solution of egg albumen 

 solution in sea-water. After about 50 minutes, some eggs in 

 the albumen solution were put into one tube of the centrifuge, 

 normal eggs were placed in the other. The eggs were then 

 centrifuged at the rate of 143/evolutions persecond for2O seconds. 

 The normal eggs all showed stratification, although the various 

 zones were not sharply marked off from each other. Of the 

 eggs in the albumen solution only a few were examined. Of 

 these ten showed not a trace of stratification, one egg showed 

 stratification, but on examination it was found that its membrane 

 had remained unswollen. Pressure experiments also showed a 

 great increase in viscosity after membrane swelling. Sodium 

 iodide and I per cent, albumen were used in these experiments. 

 It is evident that botfy Jhe reagents which cause exosmosis 

 and those which produce endosmosis, cause gelatinization or 

 coagulation of some substance fn ttye Arbacia egg. Thus all 

 parthenogenetic agents produce such ^coagulative change. 1 

 The experiments indicate that the coagulation occurs just as 



1 I have omitted mention of radium and ultra-violet rays as parthenogenetic 

 agents. I have not worked with either of these methods, and so can only offer a 

 theoretical interpretation. Judging from Loeb's description (Science, N.S., XL., 

 680 (1914)), ultra-violet rays produce membrane swelling and thus they no doubt 

 induce endosmosis. Moreover both radium and ultra-violet rays are protein 

 coagulants, according to Dreyer and Hanssen, C. R. Acad. Sci., CXLV., 234 

 (1907). Hardy has also decribed gelatinization of a globulin solution as a result 

 of radium radiation. Proc. Camb. Phil. Soc., XII., 201 (1903). 



