276 LEIGH HOADLEY. 



agglutinate to the egg. This inhibition, therefore, very evidently 

 occurs between the periods of agglutination and of activation, 

 or during the latent period. It may be said that the egg is 

 held at the latent period by the solution. As soon as the agglu- 

 tination is seen to occur, there is a block interposed, and the 

 reaction ceases. At the time when this block is first interposed, 

 there is no great harm done to the eggs. If they are removed 

 to sea-water and inseminated, the sperm penetrate and cortical 

 activation ensues. This seems to show that the action involved 

 affects only the very external parts of the gametes and is easily 

 removed. After an exposure of slightly longer duration, the 

 viability of the eggs becomes poorer, but this I would consider 

 to be due to the penetration of the salt into both the cortex, 

 and, later, the central part of the egg and consequently, to a 

 very different mechanism from that which prevents the elevation 

 of the membrane. 



There are a number of physical and chemical phenomena 

 which may be responsible for this inhibition of membrane 

 formation. The theory of chemical combination was suggested 

 by Lillie. He remarks ('21) the similarity of the effective 

 concentrations found to hold in the "cleavage toxicity" of his 

 work and in the enzyme poisoning discussed below. The physical 

 action may be of two kinds. It may be an adsorption phenom- 

 enon resulting in either a change of the electrical charge on the 

 membrane which is present before fertilization or an adsorption 

 by molecular groups. Heesch ('21) finds that the charge on cell 

 membranes of Lycopodium spores, leucocytes, and yeast cells can 

 be reversed by the use of La(N0 3 )3 solutions. Whether this 

 action is the same as that in membrane-inhibition or not, is an 

 open question. Membrane-inhibition might be due to a change 

 of charge of the egg membrane, or to an adsorption of the metallic 

 ions by some of the complex molecular groups in the egg proto- 

 plasm. Were these groups those of the activable substance, this 

 adsorption would explain the partial activation described above. 

 The first of these would involve an electrical action while the 

 latter would result in a chemical inactivation though not a 

 chemical reaction. 



Lillie ('21) noted the close similarity between the concentra- 



