32 OF VITAL MOTION. 



Section II. 

 OF vital movements in the vessels and cells 



OF ANIMAL BODIES. 



In creatures which remain at the foot of the scale 

 of existence, and in the early transitional phases of 

 beings which ultimately attain to a higher grade, the 

 vascular movements are in every respect similar to 

 those of the laticiferous system in the plant ; but in 

 more perfect states the plan is greatly altered, and 

 instead of the ever-changing centres, and the oscilla- 

 tory currents connected with them, there is a single 

 heart and a perfect circulation. In this movement 

 the heart is undoubtedly the prime agent, but it is 

 not less true, that the vessels, and especially the smaller 

 ones, possess an important complementary power, and 

 this it is our present purpose to investigate. 



The cellular movements of animal bodies are, in 

 many respects, similar to those of plants, but in 

 addition to these is one that is exhibited in certain 

 processes to which the name of cilia is given, and 

 which has attracted considerable attention in these 

 days of microscopic investigation. All these demand 

 attention in proper order. 



