Scientific Proceedings. 



(237) 67 



Acids, alkalies, salts, glucosids, and toxin diffuse into 0.9 per 

 cent, watery NaCl solution more quickly than into a similar solu- 

 tion containing agar-agar and gelatin. This reduction in rapidity 

 of diffusion increases with increase in concentration of the jelly. 

 Ten per cent, gelatin exerts a greater inhibition than two per cent, 

 agar-agar, and 25 per cent, gelatin exerts greater restraint than 

 10 per cent, gelatin. The ratio between the rate of diffusion and 

 the concentration of the colloidal suspension is, in the case of 

 gelatin, nearly inversely proportional to the square root 'of the 

 concentration of the colloid. In the case of agar-agar, with 

 which the possibility of varying the concentration is far less than 

 with gelatin, the inhibitory influence is less marked and does not 

 conform to this rule. Voigtlander's results are applicable to the 

 special case of agar-agar jelly. 



The influence of colloids upon the injurious effects produced 

 by^bile salts upon the pancreas is due, apparently, to a modification 

 by reduction of the diffusibility of the bile salts, which result 

 diminishes the concentration of the salts brought in contact with 

 the pancreatic tissues in a unit of time. 



Seventeenth meeting. 1 



Laboratory of the Department of Health, of New York {East 

 1 6th St.). May 2j, ipod. President Flexner in the chair. 

 43 ( x 35)* " Analogies between the phosphorized fats obtained 



from the brain and kidney," with exhibition of products : 



EDWARD K. DUNHAM. 



So much attention has been directed to the protein constituents 

 of protoplasm that it has become usual to regard proteins as the 

 physical basis of life. Relatively recent investigations have, how- 

 ever, indicated that all cells contain complex substances of a fatty 

 or lipoid nature, in which phosphorus and nitrogen are conspicuous 

 elements. Many of these lipoids possess remarkable physical 

 properties. In contact with water or alkaline liquids, they pass 

 into colloidal solution after imbibing large quantities of water with 

 the production of " myelin forms." They also differ from neutral 

 fats in doubly refracting light. Such physical characters and the 

 complex molecular constitution of these lipoids appear to justify 

 the assumption that they, as well as proteins, are essential con- 



1 Science, 1906, xxiii, p. 979 ; American Medicine, 1906, i (N. S.), p. 155. 



