GLAND. 



481 



tended by these writers that the last named 

 bodies elaborate from the blood certain fluids, 

 and that as far as the real function of a gland is 

 concerned, it matters not whether the secreted 

 fluid escapes by a proper excretory duct, or is 

 taken up by the lymphatic vessels; it is, in- 

 deed, supposed by liaase that these bodies, 

 like the true glands, possess excretory ducts, 

 but this opinion has received little support. 



This method of viewing the subject appears 

 to be very injudicious ; because it is based on 

 the assumption that certain organs secrete fluids 

 from the blood, but of which secretion we have 

 no evidence ; and further, because organs are 

 classed together, between which there is no 

 similarity either of structure or of function. 



In establishing a well-founded distinction 

 between parts which, in their general form and 

 outward appearance, bear a resemblance to 

 each other, it is proper to seek for some lead- 

 ing and obvious character, concerning which 

 there can be no dispute. In applying this rule 

 to the present case, we shall find that the spe- 

 cial distinction of a true gland, as contrasted 

 with those organs with which it has been assi- 

 milated, is the possession of an excretory canal 

 or duct ; and taking this as the essential cha- 

 racteristic, there is no difficulty in perceiving 

 that the glandular system in the human body 

 ought to be restricted to the following parts : 



Mucous glands, comprising, a, simple mu- 

 cous glands or follicles, dispersed over the 

 whole extent of the various mucous surfaces, 

 ither insulated or collected together, as the 

 glandulae Peyeri seu aggregatae. 6, Compound 

 mucous glands, (g. agglutinata?,) formed of the 

 preceding, collected into masses, and slightly 

 modified in their structure, comprising the 

 molar, labial, palatine, and buccal glands, the 

 lachrymal caruncle, tonsils, Cowper's glands, 

 prostate, and seminal vesicles, c, Sebaceous 

 glands, consisting of those of the skin, the 

 ceruminous glands, the Meibomian glands, d, 

 Conglomerate glands, (g, conglomeratse ;) 

 these, which are the most complex of the glan- 

 dular organs, consisting of the salivary glands 

 and pancreas, the mammary glands, the testicle, 

 the kidney, and the liver. 

 . These glands may be classed according to 

 their functions in the economy as follows : 



I. For lubrication and protection ; a. mu- 

 cous glands in all parts of the body ; b. seba- 

 ceous glands ; c. lachrymal gland ; d. lachry- 

 mal caruncle. 



II. Connected with digestion; a. salivary 

 gland ; b. pancreas ; c. liver. 



III. Connected with generation; a. testis ; 

 b. prostate ; c. seminal vesicles ; d. Cowper's 

 glands ; e. mammary gland. 



IV. For excretion ; a. kidney ; b. liver. 



By extending the principle that all glands are in 

 reality nothing but processes of the mucous mem- 

 brane ending in cul-de-sac, the lungs have, by 

 some writers, been included amongst the glandular 

 organs, the trachea, it is said, performing the office 

 of an excretory duct. It is certain, as we shall 

 subsequently show, that the lungs present, both in 

 their formation and functions, a close approxima- 

 tion to the true glands. 



VOL. II. 



The particular description of the above 

 organs and the modifications of the general 

 glandular structure they present, will be found 

 in the articles KIDNEY, LACHRYMAL APPARA- 

 TUS, MAMMA, &c. 



Situation, The principal glands are placed 

 in the head and abdomen ; in the extremities, 

 with the exception of those of the skin, they 

 are totally absent. In general they are pro- 

 tected from external injury by being lodged 

 deeply in the cavities of the body ; but to this 

 rule there are several important exceptions, as 

 the mammae, testes, parotid glands, &c. 



Organization. In the whole range of Ana- 

 tomy, whether Human or Comparative, there 

 are probably no organs which, on account of 

 the complexity of their structure, the number 

 and variety of forms which they present, and 

 the importance of their functions in the animal 

 kingdom, are more interesting than the glands, 

 or the structure of which, until within a very 

 recent period, was more imperfectly understood. 

 Even at the present time the prevailing ideas 

 respecting the essential characters of the glan- 

 dular organization are in general so vague and 

 indefinite, and but too often positively errone- 

 ous, that I feel myself called upon to enter 

 more fully into the investigation of this subject, 

 than would otherwise be necessary. Much of 

 this uncertainty has arisen from the fact that, 

 whilst the views of the immortal Malpighi, 

 founded as they are on truly philosophic 

 grounds, have never attracted that investigation 

 to which they are so justly entitled, the theore- 

 tical opinions of Ruysch, being received with 

 all the eclat inspired by his unrivalled skill in 

 vascular injections, have been generally adopted. 

 It is true that, on many minor points, Malpighi 

 was in error; and that the vagueness of his 

 descriptions, and his infelicitous comparison of 

 the ultimate divisions of the glands with clus- 

 ters of grapes or acini,* greatly assisted in pre- 

 venting his opinions being generally admitted 

 or even comprehended. But tho'se distin- 

 guished anatomists who have, by their recent 

 inquiries, at length decided the long-disputed 

 theories of Malpighi and Ruysch, have proved 

 that in all essential points the conclusions of 

 the former great authority are founded in truth. 



Minute structure. The investigation into 

 the structure of the glands, when conducted in 

 accordance with the enlightened principles of 

 philosophical anatomy, shows that the laws 

 which regulate their formation are simple and 

 definite ; and that, although Nature has dis- 

 played here, as in all her other works, immense 

 fertility in modifying the forms and characters 

 of the several glands, so as to render them effi- 

 cient to the performance of their varied offices, 

 yet in no single instance is there a departure 

 from that structure, which constitutes the type 

 of the whole glandular system. The unifbr- 



* This term, so much employed in descriptions 

 of the glands, yet so indefinite in its acceptation, 

 has caused such confusion and misconception, that 

 it is most desirable to abolish it from the nomen- 

 clature of Anatomy. In the descriptive part of the 

 present article, I shall therefore scrupulously avoid 

 employing this expression. 



2 K 



