TRANSACTIONS OF SECTION D. — DEPT. ANATOMY AND PHYSIOLOGY. 559 



On the Growth of ottr Knowledge of the Process of Secretion in the 



Animal Kingdom. 



The Vteivs of the Ancients. 



It was known to the ancients that organs of the body exist which are concerned 

 in the separation from it of excrementitious substances, although the greatest 

 doubts prevailed as to the organs to which such functions should be ascribed. 

 Thus we find Hippocrates defining it as characteristic of glands that they occur 

 in moist parts of the body ; but showing his ignorance of the true relations of 

 glands tosecretipn by connecting them with the'formation of hairs, and discussino- 

 the question which we find our own Wharton debating again in the seventeenth 

 century, and which he formulates, ' Num cerebrum ad glandularum numerum vel 

 viscerum accedat.' The general opinion of the ancients, and the opinion which 

 was adopted and taught by Galen, was that the glands were sieves or coUanders 

 (cola), which served to strain off" from the blood purely excrementitious substances. 

 The liver and the kidneys were strangely enough removed from the group of glands 

 and placed amongst the viscera. The first writer who appears systematically to 

 have treated of the glands was the before-mentioned Wharton in his * Adenographia 

 sive glandularum totius corporis descriptio.' Although this author certainly 

 added to the existing knowledge of the descriptive anatomy of secreting oro'ans, 

 his views on the functions of glands were strangely fanciful and erroneous'! 



The glands he considered to be specially related to the nervous system, the 

 viscera, so-called, to the blood-vessels ; such glands as the pancreas, and the sali- 

 vary and lachrymal glands being engaged in separating excrementitious substances 

 from the nervous system. It was in 1665 that the great anatomist Malpighi * 

 first attempted to investigate the structure of glands in a truly scientific spirit, 

 endeavouring to establish a relationship between simple glandular' follicles and such 

 complex glands as the liver. All glands he believed to contain as ultimate elements 

 bodies which he termed ' acini,' a word which in its primitive classical sense had been 

 used to designate the stone or seed of the grape or the grape itself. The concep- 

 tion, indeed, which Malpighi formed of an 'acinus' was rather that of a secretin"- 

 nodule than of an ultimate saccular or tubular recess. The 'acini,' however, he 

 believed to be in communication with the eSerent ducts of the glands to which they 

 belonged, and through which they poured out their proper secretion, derived in the 

 first instance from the blood contained in minute arteries supplied to the gland. 

 Ruysch (1606), known as the first celebrated injector of blood-vessels, finding that 

 frequently the fluids which he forced into the blood-vessels of glands escaped 

 through their ducts, or made their way into the surrounding tissues, concluded 

 that the blood-vessels communicated directly with the interior of the "-lands- these 

 he held to be organs which, according to the views that had long prevailed, 

 merely strained off from the blood certain of its more liquid constituents. The 

 views entertained by the most eminent of the supporters of Ruysch, the illustrious 

 Haller, were expressed by him as follows. After defining the term ' acinus ' to 

 signify the ultimate division of a gland, he remarfa that ' the acini consist of 

 congeries of vessels, bound firmly together with a cellular web, containing an 

 excretory duct in their interior, which commences from the most minute arteries 

 by small ducts impervious to the blood. ... So that secretion diflers from the 

 ordinary circulation of the blood in this particular, that the smallest arteries are 

 continuous with veins of equal or greater size, capable therefore of receiving the 

 blood, whilst the excretory ducts are much smaller, in order to eflect the separa- 

 tion of the secretion.' * The advocates of the Ruyschian theory were compelled to 

 have recourse to the most improbable hypotheses to explain the diversity of the 

 secretions of different glands, as for example, that different glands secrete difl'erent 

 liquids, because of the difference in the diameters of the pores by which the blood- 

 vessels communicate with the glands ; that the different arrangement of blood- 



' Malpighi, Exercitatio Anatoviica de Ilenilnis. 

 » Haller, p. 275. 



