326 L. V. HEILBRUNN. 



The eggs which were allowed to remain in the acid sea-water 

 also formed a few polar-bodies. 



Potassium Hydroxide. Eggs were placed in 40 c.c. of sea-water 

 plus i c.c. n/io KOH. In this solution membrane swelling 

 occurred. The eggs formed polar bodies while in the alkaline 

 medium. The first polar body observed was noted after 16 

 minutes exposure. After 33 minutes, a count gave 14/100 with 

 polar bodies. 



Potassium Cyanide. Eggs were placed in a 0.04 per cent. 

 KCN solution, made by diluting 5 c.c. of 2 per cent. KCN up 

 to 250 c.c. with sea-water. During the experiment the cyanide 

 was not allowed to evaporate, for it was kept in a tightly 

 stoppered weighing-tube. After a 36 minute exposure a count 

 showed 28/100 of the eggs with polar bodies. The potassium 

 cyanide caused membrane swelling probably because of its alka- 

 line reaction. 



Hypertonic Sodium Chloride Solution. In the experiments with 

 acids and alkalies and with sodium iodide the solutions used 

 were approximately isotonic with sea-water. In the course of 

 some other work it was noticed that solutions made by adding 

 2\ M NaCl to sea-water caused membrane swelling. Hence it 

 was expected that these solutions would also cause polar body 

 formation. Eggs were exposed for 7 minutes to a solution made 

 by adding 5 c.c. of 2| M NaCl to 25 c.c. of sea-water. As a 

 result 21/100 of the eggs formed polar bodies. 



To sum up, in all of these experiments the swelling of the 

 vitelline membrane was in every case followed by the throwing-off 

 of polar bodies in a large percentage of the eggs. The controls of 

 untreated eggs did not form polar bodies. In these experiments 

 with reagents which cause membrane swelling there were no 

 failures. No reagent could be discovered which would produce 

 swelling of the vitelline membrane without at the same time 

 causing the eggs to mature. 



RUPTURE OR REMOVAL OF THE MEMBRANE. 



There is a third way in which the Cumingia egg may be freed 

 from the binding pressure of its vitelline membrane. If the eggs 

 are shaken vigorously, oftentimes a certain percentage of the 



