408 



NA TURE 



\August 24, 1882 



"acini" a word which in its primitive classical sense has been 

 used to designate the stone or seed of the grape or the grape 

 itself. The conception, indeed, which Malpighi formed of an 

 "acinus" was rather that of a secreting nodule than of an 

 ultimate saccular or tubular recess. The " acini" however, he 

 believed to be in communication with the efferent 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. Kuysch 

 (1696), 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 glands ; 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 remarks that "the acini consists 

 ■of congeries of vessels, bound firmly together with the cellular 

 web, containing an excretory duct in their interior, which com- 

 mences from the most minute arteries by small ducts impervious to 

 the blood. . . . So that secretion differs from the ordinary circu- 

 lations 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 effect the separation of the secretion." 

 (Haller, p. 275.) The advocates of the Ruyschian theory 

 were compelled to have recourse to the most improbable hypo- 

 theses to explain the diversity of the secretions of different glands, 

 •as, for example, that different glands secrete different 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-vessels, the mode in which they divide, the 

 resistance which they offer to the flow of blood through them, by 

 modifying the pressure and velocity of the blood-flow' through 

 the organ, induce secretions varying in character. It is strange 

 to learn from Haller, as was indubitably the fact, that the great 

 majority nf his contemporaries, such men as Peyerand Vieussens, 

 and even Boerhaave, adopted the Ruyschian view of the struc- 

 ture of glands. The opposition to Ruysch came first from 

 Ferrein (Ferrein, " Sur la Structure des Glands," &c, Mbnoircs 

 de VAcad. Roy. cits Sciences de Paris, 1749I, who maintained 

 that the kidneys essentially consist of an assembla e of convoluted 

 tubes, which he looked upon to be the seat of the renal secretion 

 — tubes which a subsequent investigator, Schumlansky (Schum- 

 lansky, " Dissertatio Inaugur. Anatomica de Renum structur.i, 

 A gentoreti, 18S0), looked udon as taking their origin in the 

 acini of Malpighi, to which he referred the active part in secre- 

 tion. Then followed the researches of Mascagni and Cruiekshank, 

 who found, by injecting quicksilver into the malum iry glands, 

 that the ramification of the ducts of this organ terminate in 

 racemose follicles ; though Ma cagni still admitted a connection, 

 by means of open pores, between the sides of the glandular blood- 

 vessels and the interior of the glands themselves. It was 

 unquestionably Professor £. H. Weber, of Leipzig, who 

 completely demolished the Ruschyian hypothesis, and who by 

 numerous researches on the salivary glands of birds and of 

 mammals, and on the pancreas of birds, established the general 

 fact of the terminatio 1 of gland ducts in blind extremities, 

 though with modesty he put forward his opinions as confirming 

 the inductions of Malpighi, expressing himself as follows : 

 " Admirably did Malpighi avail himself of the structure of the 

 liver in the lower animals, and to the embryo of the higher, s a 

 foundation-stone for his opinions ; for the arrangement of the 

 whole glandular system speaks for itself, inasmuch as it simply 

 consists of single, compact, holliw, blind canals, more or less 

 numerou , floating in the fluid which surrounds their organs ; and, 

 alihough these ramifications are drawn out between the branches 

 of the blood-vessels, there is no immediate passage from one to 

 the other." 



The Researches of Johannes Muller. 



Such was the state of knowledge in reference to the structure 

 of secreting' glands and secretion at the time when the great 

 Johannes Mullet undertook the investigation of which the re-ults 

 were first of all published in the memorable work entitled " De 

 •Glandularum secernentium Structura penitiori earumque prima 

 Formatione" (Lip--. 1S30). It is impossible not to sympathise 



with the reflection of Professor Heidenhain, recently made in 

 reviewing the researches of Johannes Muller in connection with 

 this subject (Heidendain in Hermann's " Handbuch der Phy- 

 siologic," vol. v., 1880, p. 6.), to wit, that the physiologists of 

 today may be accused of ingratitude for having allowed the great 

 name of Johannes Muller to have well-nigh disappeared from the 

 pages of physiological literature. We forget that this man — this 

 giant in the field of biology as he is appropriately termed by 

 Heidenhain, the last man of whom perhaps it will ever be said 

 that he was at once the greatest comparative anatomist of his 

 time and the most philosophical and original of all contemporary 

 physiological writers — by his own researches, and particularly by 

 the one which concerns us to-day, influenced the progress of 

 physiology, at a most critical period, more than any other man. 

 He was not, like his contemporaries Magendie and Flourens, a 

 great physiological experimenter, though he showed that he well 

 appreciated the value of experiment in advancing our science ; 

 but he was pre-eminently a physiologist who recognised the 

 immense importance of a close study of structure, not only 

 because of the interest which it presents to the pure and philo- 

 sophical morphologist, but because of its absolute necesity, if we 

 are to penetrate at all deeply into the secrets of animal function. 

 Muller, in the first instance, had convinced himself, by the study 

 of the circulation of organs sufficiently transparent to permit of 

 it, especially the circulation through the liver of larval sala- 

 manders, that, in glands, arteries never end in any other mode 

 than by capillaries leading into veins. He then set himself to study 

 in the case of most glands, and in a large variety of animals, the 

 relationship of gland ducts to the truly secreting parts of the 

 organ, and the relation of the blood-vessels to these. Basing 

 himself upon these anatomical studies of adult organs, and upon a 

 careful study of the development of gland, — a study which had 

 been ai tempted slightly by Malpighi, and more satisfactorily in 

 the case of the parotid by E. H. Weber (E. H. Weber, 

 " Beobachtungen iiber die Structur einiger conglomerirten und 

 einfachen Driisen und ihre erste Entwickelung." MicVti'sArcAiv 

 for 1827, p. 274) — Muller came to the conclusion that all glands 

 possessed of a duct are only involutions more or le>s complex of 

 membranes, the largest number being involutions of the external 

 investment of the body or of the membranes opening upon its 

 surface. The following are the general results relative to the 

 structure of glands which Muller deduced frem the anatomical 

 study of individual organs : — * 



1. However various the forms of their elementary parts, all 

 secreting glands without exception (sot only those of the human 

 body, but all met with in the animal kingdom) follow the same 

 law of conformation, and constitute an uninterrupted series from 

 the simplest follicle to the most complex gland. 



2. No l ; ne of demarcation can be drawn between the secreting 

 organs of invertebrata and those of vertebrate animals; not 

 merely do we meet with the simplest sacs and tubular secreting 

 organs, like those of insects, in the higher animal-, but there is a 

 gradual transition from these simple secreting organs to the 

 glands of the most perfect vertebrata. 



3. All glands agree in affording by their interior a lanre 

 surface for secretion. The varieties of internal surface by which 

 the great end — extent of surface in a small space — is attained, are 

 very numerous. 



4. Acini, in the hypothetical sense in which the term has been 

 used by writers — in the sense viz. of secreting granules— do not 

 really exist ; there are no glomeruli of blood-vessels with ducts 

 arising from them in a mysterious way, as has been supposed, 

 whatever notions may have been held regarding them. 



5. The parts described as acini are merely masses formed by 

 the agglomeration of the extremities of the secreting canals ; 

 frequently, indeed, they are formed of minute vesicles aggregated 

 together in grape-like bunches, which may be injected with 

 mercury, and are often su-ceptible of inflation. 



6. In many glands which have been incorrectly described to 

 have acini or secreting granules, there are not even the hollow 

 vesicular acini; the [secreting tubes, instead of terminating in 

 vesicles or cells, form long convoluted canals or straight tubuli or 

 short creca. 



7. It has been demonstrated in the case of all glands that the 

 blood-vessels are not continuous with the secreting tubes — that 

 the minute vessels bear the same relation to the coats of the 

 hollow secreting canals, and their closed extremities, as to any 



1 This abstract of Mailer's general conclusions has been abbreviated from 

 the sections treating on this subject in his "Elements o (Physiology." See 

 Translation by Mr. Ealy, London, 1138. vol. i. p. 456, et scq. 



