118 GENERAL ANATOMY OF THE TISSUES. 



the intestinal follicles, it is doubtful whether they excrete substances 

 into the intestine, or receive them from thence to give them up again to 

 the vessels. In the lymphatic glands, the ducts supply the glandular 

 follicles with matters which they take up again when further elaborated. 



The development of the blood-vascular glands is still very obscure ; 

 although this much appears certain, that most of them are developed 

 without the participation of the intestinal epithelium, either from the 

 fibrous wall of the intestine or from the same blastema as that which 

 produces the sexual glands. The thymus and thyroid alone are to be 

 regarded, according to Remak, as diverticula of the intestinal canal. 



The nutrition of most of these glandular structures is very energetic, 

 as the abundance of the blood they contain and their frequent morbid 

 alterations show: the hypophysis cerebri and the supra-renal capsules 

 alone, in this respect, occupy a lower grade. 



Literature. A. Ecker, art. " Blood-vascular Glands," in "Wagner's 

 Handw. d. Phys.," Bd. IV. 1849. [H. Gray, " On the Development of 

 the Ductless Glands in the Chick," Philosoph. Trans., 1852. TRS.] 



