The Influence of External Factors on Development 169 



The extensive treatment of Fundulus eggs with salt solutions 

 which Mathews ('04)- has recorded goes to show that the egg 

 membrane is easily permeable. 



To demonstrate further the permeability of the membrane, 

 during the first hours of development, I carried out the following 

 experiment. Since embryos had been found to be affected in a 

 definite manner by solutions of LiCl below the strength of ^ m, I 

 determined to subject them for short periods while in the two-cell 

 stage to strong solutions of LiCl. Eggs were placed in a molecu- 

 lar and a double molecular solution of this salt in distilled water; 

 one hour and ten minutes later they were all quite abnormal, 

 showing the lithium effect. Some of these were then transferred to 

 sea-water and on examination, eleven hours later, still showed the 

 lithium abnormalities. Those left in the LiCl solution were all 

 badly plasmolized or shrunken while the blastodermic cap was 

 heaped up upon the top of the yolk, almost pinching away from it. 

 Some eggs were removed from the double molecular solution after 

 staying two and one-half hours in it, these failed to recover, and 

 were in the same condition after sixteen hours as those still in the 

 solution. Those removed from the molecular solution after one 

 hour were in the following condition after forty hours; many were 

 dead but some had recovered and showed the embryonic thicken- 

 ing forming on the egg. Of those that spent two and one-half 

 hours in the solution one or two were still living though abnormal, 

 the germ ring having descended only one half of the way down the 

 yolk, and in one case an embryonic shield had formed. 



Those taken from the double molecular solution after one hour 

 were, forty hours later, almost all dead, the fev/ living ones being 

 very abnormal. Those that remained two and one-half hours in 

 this solution were all dead. 



- Mathews tried with these eggs to ascertain the relation if any between the properties of the elements 

 and their physiological action. He concluded that the poisonous action of any cation or metal upon the 

 eggs varied inversely with the solution tension. "Those ions with a very low solution tension are very 

 poisonous; those with a high tension are relatively inert. The poisonous action of any anion also follows 

 this rule/' Further "there is an inverse relationship between atomic volume and poisonous actionj and 

 a direct relationship between equivalent weights and poisonous action. Poisonous action of the metals 

 is a periodic function of their atomic weights. Elements which have a low atomic volume and high 

 equivalent weight, as mercury, are more active than those with a high atomic volume and a low equiva- 

 lent weight, as sodium.'' Many exceptions to the foregoing were found. 



