192 BIOLOGICAL PHYSICS 



the elements of which the secreted fluid is composed, 

 and that the lymphatic circulation is concerned merely 

 in conveying, or removing, the results of the gland 

 tissue waste, proceeding from the functional activity 

 of the gland structure proper. If this be so, and we are 

 unable to conclude otherwise, we see, in every secretion, 

 the results both of blood and neural fluid disposal, some 

 of which must be regarded, as supplying materials for 

 further functional purposes in the economy, and some, 

 as removing from these circulations, for hygienic reasons, 

 materials whose continued presence there has become a 

 menace to health, and whose removal has been thereby 

 a physiological necessity. 



Secretions of both descriptions may be cited, in order 

 to illustrate the truth of these remarks thus, as types 

 of secretions whose value consists in aiding the vital 

 working of the body, we select first the ductless glands, 

 which secrete materials destined to continue in, and to 

 affect the physiological working of the blood, and second 

 the kidneys and sweat glands whose office it is to 

 separate, and to eliminate, materials altogether effete, 

 and exhausted of further functional usefulness. Of the 

 mixed class of secretions, we would cite third those 

 formed along, and connected with, the lumen of the 

 alimentary canal, whose chemico-physical powers, as 

 digestive agents, are still utilised for great physiological 

 purposes, and whose re-absorption in, and amongst, the 

 digested pabulum, in a consequently modified form, is 

 again effected. 



In regarding the ductless glands as great agents in 

 the elaboration and vivifying of the blood plasma proper, 

 we think we perceive a great meaning in the expression, 

 and realise that a ductless state of those glands is not 

 only consistent with, but a necessary structural condition 

 for, enabling them to retain, and pass on, in the blood 

 circulation proper, the entire results of their functional 

 activity unaffected by admixture with adynamic, or 

 noxious, substances, and physiologically capable of meet- 

 ing the material and dynamic necessities of nutrition, 

 throughout the organism. 



Secretion, therefore, becomes a function of a most 



