320 WILSON GEE 



days after treatment the tentacles slowly accepted food, how- 

 ever, not in an entirely normal manner. Inclining with the 

 piece of oyster, they dropped it over on to the disk to be ac- 

 cepted by the mouth. 



In the case of the 3/8 M Mg S0 4 , the individuals showed con- 

 siderable variability. Three of the five specimens treated showed 

 a similar though less intense effect to that produced by the 

 normal solution ; the other two accepted food upon expanding a 

 few minutes subsequent to their treatment. 



With regard to the action of magnesium salts Cushny (1910) 

 says: "The magnesium salts have recently been shown by 

 Meltzer , to have a very powerful action when injected hypo- 

 dermically or intravenously. The most characteristic effect is 

 complete anesthesia, resembling that induced by the chloroform 

 group and ending in fatal cases in paralysis of the respiratory 

 centre." 



The effect of magnesium sulphate upon anemones is known 

 to all who. have ever preserved specimens of these forms. The 

 condition of anesthesia produced in the animal prevents its 

 contraction upon the addition of the preserving fluid, and the 

 specimen is secured in an expanded fixed condition. Thus the 

 irresponsiveness of the Cribrina in these experiments is to be 

 attributed to the anesthesia produced as the result ot these 

 injections. There seems to be produced also a paralysis of 

 the muscular fibrils of the cells of the body. 



EXPERIMENTS ON THE NORMAL FEEDING REACTIONS OF CRIBRINA 



The experiments of Parker (1896) on Metridium were re- 

 peated on Cribrina and it was found that the tentacles of the 

 left side accepted pieces of oyster given it for eight successive 

 times. The oyster was then given to the right side and was 

 immediately accepted. For the two succeeding times food was 

 taken by them, but subsequent tests gave a refusal in this 

 region. This is to be accounted for, I believe, as the effect of 

 the diffusion of the food juices in the water causing the pro- 

 duction of mucus in addition to that caused by the actual con- 

 tact with the food. No doubt what von Uexkull would term 

 a "withdrawal of tonus" from the tentacles to the region of 

 the mesenteries also takes place due to the secretion of digestive 



