54 THE ROYAL SOCIETY OF CANADA 



as chloroform and ether, produce changes of type II which are probably 

 irreversible, and a result of the complex phenomena of death rather 

 than an immediate reaction to the applied agent. 



Meaning of the changes.— The discovery that electrolytes are 

 efïective in producing the changes in question in general proportion 

 (the exceptions are explicable) to their precipitating action on colloids 

 suggested use of the ultra-microscope to see if any such precipitation 

 could be detected in the living protoplasm. By selecting suitable 

 material with scanty pyrenoids one may obtain a picture in which the 

 chloroplasts appear dead black except for a faint outline and the 

 bright periphery of the pyrenoids. Soon after contraction sets in 

 there appears a faint luminosity, due to specks of light, which increases 

 as time goes on but remains slight as long as the liquid phase lasts. 

 In the second type of contraction the luminous specks increase rapidly 

 while faint needles of light may also be seen, resembling a much 

 reduced picture of fibrin coagulation in blood. The whole picture 

 represents different stages in the precipitation of an emulsoid. That 

 it is a gel rather than a sol we are dealing with probably matters 

 little, as the difference between them seems to lie only in the degree 

 of approximation of the particles.^ Precisely what happens during 

 the precipitation of an emulsion colloid is not yet known. The first 

 step seems to be loss of water by the highly hydrated colloidal elements. 

 One result of this is a greater difference of refractive index of the two 

 phases and the development of a reflecting surface — a. transition from 

 an emulsoid to a suspensoid condition, as Michaelis has described it. 

 It may be either these dehydrated particles or agglutinations of them 

 that give the first appearance of light in the field. A concomitant 

 result of transference of water from internal to external phase would 

 naturally be a lowering of viscosity, permitting the chloroplasts to 

 change form under surface tension. Further precipitation until the 

 particles unite may be termed coagulation and is followed by con- 

 traction of the whole body (syneresis) with expulsion of water. 

 With some agents the cytoplasm may remain unaffected up to this 

 stage, but later it too goes through similar phases of precipitation. 



The intermediate type in which a solid contraction of the chloro- 

 plast as a gel precedes the more liquid condition, is different from 

 type II inasmuch as no visible coagulum is formed, but may be of a 

 similar nature if syneresis of agar is comparable to that of blood. 



Applications.— R.. Chambers,'^ in his micro-dissection studies, 

 found a lowering of viscosity to immediately precede the rise that 

 accompanies death He regarded this lowering as post mortem, but 

 these experiments show that a similar fluid stage may be ante mortem 



