TRAXSACTIOXS OF SECTION D. DEPT. ANATOMY AND niYSIOLOGY. 569 



The liiMEDiATE Source of the Nutriment consumed by the 



G LAND-CELL. 



lu the original scheme of a secreting gland, developed first of all by Bowman, 

 then adopted by Goodsir, Carpenter,' and many other writers, the essential struc- 

 tural elements taken into account were the following: — 1. Epithelial cells lining 

 the secreting cavity of the gland; 2. Sub-epithelial tissue, usually presenting 

 .superficially the form of a basement membrane, upon which the cells were placed ; 

 and .3. a' capillary network in closer relation to the basement membrane, or 

 more superficial part of the sub-epithelial tissue. In harmonj' with this scheme, 

 the glandular elements were always spoken of as drawing their supply from the 

 blood in the capillaries. The one element which was wanting in that scheme, and 

 which we are able to fit into it, thanks again to the labours of the great physiologist 

 of Leipzig, is the relation of .so-called lymph-spaces to the other elements. As was 

 first shown by the researches of Ludwig and his school, amongst the modes of 

 origin of the peripheral lymphatics, the most numerous are to be foimd in connective 

 tissue, and nowhere more abundantly than in the connective ti.ssue of glands, which 

 is everywhere interpenetrated by irregular spaces containing lymph, from whence 

 spring the minutest lymphatics. If we consider, then, the immediate environment 

 of the secreting cell, we find that in close proximity to it is the lymph, which is a 

 transudation from the blood, and upon which the gland-cells are directly dependent 

 for all the matters which they require. For a certain time, then, the gland-cell 

 will be independent of the supply of blood, that is, so long as the lymph surround- 

 ing it contains a sufficient quantity of essential matters, of which oxj'gen is one of 

 the chief, to support its life, or until it becomes so charged with waste products derived 

 from cell life, e.g. COo, as to interfere with the functions of the latter. It certainly 

 appears that, at least in the majority of cases, it is the secreting cell which modifies, 

 in the first instance, the composition of the lymph which bathes the tissues in 

 proximity to it, rather than the composition of the lymph which modifies the ac- 

 tivity of the gland-cell. There are some cases nevertheless in which it would appear 

 that the presence of certain constituents in the lymph is the direct cause of the 

 activity or increased activity of the cells. 



Secreting Cells peesent dtffeeext Appearances, corresponding- to dif- 

 ferent States of Functional Activity. The Researches op Heidenhain. 



Amongst the physiologists of Europe who have most enriched science by their 

 researches during the last thirty years is imquestionably Professor Heidenhain of 

 Breslau, who has exhibited his mastery of the physical side of physiology by his 

 classical research on the relations between the heat evolved in and the work done by 

 muscle, and as a biologist able to use in the best manner all the resources of modern 

 histology in the elucidation of bodily function, by the researches to which I wish to 

 direct your attention for a few moments. 



The glands imbedded in, or the ducts of which open upon the surface of the 

 mucous membrane of, the alimentary canal, for the most part, are characterised by 

 periods of more or less complete cessation of activity, as judged by the diminution, 

 or absolute cessation, of the secretion which they prepare. This is true of the sali- 

 vary glands and of the liver, but particularly true of the gastric glands and the 

 pancreas. 



Certain of these glands, i.e. the salivary glands in some animals, and the stomach 

 and pancreas in all in which they exist, have the task of preparing juices which 

 contain certain so-called unformed or unorganised ferments or enzymes, upon which 

 the properties of the secretions in great measure depend. Heidenhain in a long 

 series of investigations, which have been taken part in by certain other scientific 

 men, as by Ebstein and Griitzner, by Kuhne and Lea, and particularly 1)y Mr. 

 Langley of Trinity College, Cambridge, has shown that the secreting cells of a par- 

 ticular gland, as for instance of the submaxillary gland, of the gastric glands, and 



' Carpenter, in his admirable article on ' Secretion ' in Todd's Cyclopccdia of Ana- 

 tomy and Physiology. 



