mollgaard's reticulum 341 



due to the freezing of dilute solutions of these substances is 

 exactly similar to the appearance of a section through a paren- 

 chymatous plant tissue. Molisch casually remarks that his 

 studies confiiTn this statement. Furthermore, Ambronn states 

 that in an optical respect the walls of the meshwork in the frozen 

 colloids named are entirely similar to the walls of plant cells, 

 showing a strong double refraction and the same orientation of 

 the optical elasticity ellipsoid as do the cell-walls. 



From the observations and references presented, it must be 

 clear then that on freezing there is a separation of water from 

 the substance in question. This fact has long been known to 

 many observers (Miiller-Thurgau, Molisch, Fischer, Wiegand, 

 and others). The water separating out under the reduced tem- 

 perature forms ice, which, omitting for the present the details, 

 by displacement of the substance produces the network or sponge- 

 like structure described. The great part played by this water 

 separating out during the freezing of the substances and tissues 

 under consideration, may be further realized by a study of smears 

 of egg-albumen, fresh neural, liver, and pancreatic tissues thor- 

 oughly evaporated or desiccated in an oven. Such preparations 

 show networks somewhat suggestive of those produced by freez- 

 ing. So similar are the processes of freezing and desiccation, 

 in producing a loss of water, says Fischer, that the curve for the 

 loss of water by freezing may be calculated, for some colloids 

 at least, from the curve for the lost of water by desiccation, 

 Matruchot and Molliard have compared the separation of water 

 during freezing to plasmolysis; and, wilting, or slow and rapid 

 desiccation, as well. 



Noting the comparative unifonnit}^ of the results arrived at 

 by many observers regarding the fundamental principles under- 

 lying the freezing of numerous simple substances, colloids, and 

 plant and animal tissues we may consider, as does Molisch, and 

 with considerable support, that the cells of a plant or animal 

 tissue may be regarded, as far as their behavior in freezing is 

 concerned, as aggregate masses of solutions, emulsions, and col- 

 loids. Thus, for explanatory purposes, we may consider that 

 neural tissue with all its various elements consists of a complex 

 aggregate of solutions, colloids, and emulsions, one within the 



