4 ° CONNECTIVE TISSUES. [sect. 22. 



form of the ultimate elements, be classified under the following 



divisions : — b 



i. Glands with shut vesicles, which burst occasionally, or remain 

 constantly shut. Ovaries, thyroid. 



2. Glands whose parenchyma consists of reticulated cells. Liver. 



3. Racemose glands, in which collections of roundish or elongated 

 vesicles are seated upon the ultimate terminations of the excretory 

 ducts. J 



a. Simple, with one or some few lobules. Mucous glandules, 

 sebaceous glands, Meibomian glands. 



b. Compound, with numerous lobules. Lacrymal glands, sali- 

 vary glands, pancreas, prostate, Cowper's and Bartholin's glands 

 mammary glands, lungs. 



4- Tubular glands, whose secerning elements have the form of 

 tubes. 



a Simple, consisting of but one or some few tubes, terminating 

 m blind extremities. Tubular gastric and intestinal glands, 

 uterine glands, sudoriferous and ceruminous glands. 



b. Compound, with numerous branches, and, perhaps, reticularis 

 united canals. Testicles, kidneys. 



Literature.— 3. Muller, Be Olandularum Secernentium Structura Penitiori. 



ips. 1830 ; H. Meckel, Mikrographie einiger Briisenapparate niederer Thiere 

 in Mull. Arch. 1846; Fr. Letdig's Comparative Anatomical Treatises in 

 Zeitsc/i.f. wtss. Zoologie, and Unterstich. ilber Fische und Reptilien. Berl. 1853. 



2. Tissues of Connective Substance. 



§ 22. General Characters of Connective Substance.— -The tissues 

 belonging to this group, viz., mucous tissue, cartilage, elastic and 

 connective tissue, as also the tissue of the bones and teeth, present, 

 both m a histological and chemical point of view, such manifold dif- 

 ferences, that it is, properly speaking, only the genetical connection 

 between them, and their correspondence in function, which keeps them 

 together. In the latter respect, connective substance serves as a sup- 

 port and investment for all the other parts of the body, and might even 

 be designated with a still more general expression, viz., 'substance of 

 support/ or < sustentative substance/ As such, it forms, firstly 

 the solid framework of the whole body (cartilages, bones and liga- 

 ments of the internal skeleton; the external skeleton — except the 

 horny structures — free cartilages and bones of internal parts) ; se- 

 condly, the investment of groups of organs, single organs or parts 

 of organs (corium, mucous membranes, fibrous membranes, sheaths 

 of muscles, nerves and glands, vessels) ; thirdly, and lastly a 



