LAWS OF SOLUTION 



results obtained by the plasmolytic method have recently been called in 

 question, because no regard has been taken of the power of the colloids 

 of the cell to absorb (imbibe) water (see page 63). 



The methods of hemolysis and plasmolysis have been used for the inves- 

 tigation of many problems in medicine besides those pertaining strictly to 

 osmotic pressure. In the case of certain toxic fluids, such as snake venom, 

 tetanus toxin, etc., determination of the hemolytic power has proved of 

 value in roughly assaying the damaging influence on other cells than 

 blood corpuscles. Studies in hemolysis have also been especially valuable 

 in working out the mechanism by which cellular toxins in general develop 

 their action, and the conditions under which this action may be counter- 



Fig. 3. To show plasmolysis in cells from Tradescantia discolor. A, normal cell; B, 

 plasmolysis in 0.22 M. cane sugar; C, pronounced plasmolysis in 1.0 M. KNO3; h, the cell 

 wall; p, the protoplasm. (After De Vries.) 



acted, as by the development of antibodies. Furthermore, any solution 

 that is to be injected into the animal body, either intravenously or subcu- 

 taneously, should first of all be tested by the above methods in order to 

 find out whether it is isotonic with the body fluids. If a hypertonic so- 

 lution is injected, it will result in the abstraction of water from the tissue 

 cells, whereas a hypotonic solution will cause the water content of these to 

 increase. Advantage has recently been taken of this water-abstracting 

 effect of hypertonic solutions in the treatment of wounds. By constantly 

 bathing them with strong saline solutions, an outflow of water is set up 

 from the tissue cells that border on the wound, and this tends to bring to 

 the focus of infection the defensive substances that are present in animal 

 fluids. 



