220 Canadian Record of Science. 



cytes of the blood correspond to the original undifferenti- 

 ated embryonic cells, which alone have made up the entire 

 embryo, and are preserved as floating organisms with a 

 latent capacity for further development, much light is 

 thrown upon both physiological and pathological processes. 

 "Whatever the view that finally prevails as to their relations 

 to invading micro-organisms, there can be no doubt that as 

 scavengers, porters, or phagocytes their function is of great 

 importance ; yet, apart from a consideration of their origin, 

 this can be but indifferently understood. It is well known 

 that the undifferentiated cells of the embryo are more or less 

 amoeboid organisms ; hence, it is perfectly natural that 

 their descendants should, under suitable circumstances, ex- 

 hibit those qualities which recent investigators are showing 

 more and more that they possess. The great part they 

 play in inflammation is also more readily comprehended. 

 In this condition there is a profound alteration in the 

 environment, as will be shown later. 



At present our positive and clear knowledge of the red 

 cells of the blood is confined to their oxygen-carrying func- 

 tion ; but I feel satisfied that this does not include all their 

 work and that we must look for a very considerable en- 

 largement of our' knowledge of the range of their duties. 

 Indeed, it would seem that we are in great danger now of 

 going to an extreme the opposite of that of our ancestors, 

 and attributing too little to the blood, especially its cells. 

 It is not to be forgotten that the blood as a whole is to be 

 regarded as a tissue, and there is no more reason why this 

 tissue should be devoid of functions than any other. 



Most of our works on physiology so present the subject 

 to the student that he has no clear ideas as to how the blood 

 does minister to the tissues, though everyone is ready to 

 say at once that the function of the blood is " to nourish 

 the tissues." In truth, some very remarkable doctrines 

 have been taught in regard to the relations of the blood 

 and bloodwessels. As a rule, students have the most misty 

 notions of the relations and importance of the lymph. They 

 know that it flows in " the lymphatics," that it gets into 



