ON GLANDULAR STRUCTURES 203 



said not to excrete, but which, we have already contended, 

 is no exception to the rule. 



Arranging gland structures around the principle, or 

 function, of secretion, and on parallel lines with that of 

 circulation, regardless of their anatomical structural 

 arrangements, as to ducts, or no ducts, we shall begin 

 and continue their survey and classification along the 

 lines by which the elements of food are taken into the 

 system, utilised and finally disposed of, as excretionary 

 matter. Accordingly we would recognise the alimentary 

 canal, or tube, as the great and primary secretory organ, 

 or gland, whose ofHce it is to secrete, or select, from the 



O * 



materials passed through it, the raw materials, or elements, 

 out of which the secretory organs beyond can expiscate 

 and select the various nutritive, or plasmic, materials 

 required by the various structures and organs of the 

 body : this great primary secretory process being effected 

 by the mucosa lining it, assisted by the countless glandular 

 agencies and effluents with which it is surrounded and 

 inter-penetrated, assisted by its own vermicular manipu- 

 lative action and mechanical trituration. Next, and 

 originating in the wall of the intestinal canal, the vascular 

 textures of the blood circulation and lacteals take up 

 and continue the process of secretion, and dispose of their 

 products of the blood directly, and to the mesenteric, or 

 chyliferous, vasculature, with its peculiar and vivifying, 

 glandulature and long ducts, ending in the blood vascu- 

 lature, which blood vasculature conveys it to every texture, 

 after leaving the left side of the heart, for a renewed process 

 of secretion, and selection, by the lining membrane of its 

 ultimate, capillary distribution, and endothelial cell osmosis. 

 This process of secretion, may be called the process of 

 nutritive secretion, and assimilation, or nutrition proper, 

 and the last stage in the integrative disposal of the nutri- 

 tive plasma, in its course of metabolic, or rather anabolic, 

 change. Secretion is a process, therefore, in which a great 

 variety and number of tissues, besides the proper gland 

 structures, take part, and may be said to constitute the 

 whole processes of digestion, gastro-intestinal absorption, 

 chyle and blood circulation, and tissue assimilation, or 

 formative disposal, of organic plasma ; which organic 



