1904.] on Breathing, in Living Beings. 481 



however, as long as the boundary surface, skin, or otherwise is per- 

 meable to gases and no great respiratory exchanges are necessary. 



Before showing you some lantern slides, I should like to point out 

 how one process is made to aid another. 



Motion associated with respiratory processes. 



Ciliary motion with respiration and the capture of prey for food. 



The old idea of one function for an organ is exploded. One 

 speaks of one man one vote. One man one value. It is not really 

 so. 



With Shelley we may say— 



" Nothing in this world is single ; 

 All things, by a law Divine," 

 In each other's being mingle." 



As regards the surfaces for these respiratory exchanges for diffuse 

 respiration, it may take place through the inner surface of the body 

 cavity of coelenterates, the under surface of the bell of a medusa, the 

 tentacles of an echinus, the respiratory tree at the hind gut of the sea 

 cucumber, or the intestine of the young of the dragon dy, or by the 

 intestinal mucous membrane of the mites which have no lungs or 

 other directly respiratory organ. In the higher animals we have 

 tracheae, gills and lungs. 



In some animals, the respiratory mechanism is closely related to 

 the motor apparatus, as in some Crustacea. In some moUusca the 

 nutritive and respiratory mechanisms are closely related. In the 

 highest of all there is central apparatus — gills or lungs — ^for the 

 respiratory exchange between the blood and the air, and a circulatory 

 apparatus for carrying the blood to and from the respiratory organs. 

 The adaptivity of insects to varied conditions of oxygen supply is 

 marvellous. 



Before showing some classical experiments and illustrating the 

 principles already laid down, I should like again to draw your 

 attention to the association of several processes with respiratory 

 mechanisms. 



[The lecture was illustrated by means of lantern slides, showing 

 the respiratory mechanisms from the lowest to the highest animals, 

 and also by a number of experiments dealing with the chemical 

 exchanges in the process of respiration. Lastly, the classical experi- 

 ment of John Hunter, on the pneumaticity of the bones of birds, was 

 shown in the duck. A candle flame was extinguished when held in 

 front of the divided trachea, when air was blown into the divided 

 humerus bone of the wing.] 



rw. s.] 



