THE BLOOD AND THE LYMPH. 



341 



Fig. 294. 



mode of development, so far as I have seen, obtains in all 

 animals, without exception, in which capillaries exist, and 

 the various objections offered 

 to the exposition given by 

 Schwann and myself, have 

 chiefly arisen in the notion, 

 that every network connect- 

 ing the arteries and veins in 

 embryos, is a capillary plexus. 

 This, however, is by no means 

 the case, and consequently 

 the circumstance, that the 

 wrongly termed capillaries of 

 the germinal area arise after 

 the type of the larger vessels, 

 is not an objection of the least 

 weight in opposition to us. 



The capillaries of the lym- 

 phatic system, which may be 

 readily traced in the tail of 

 batrachian lama (fig. 228), 

 exhibit, essentially, precisely 

 the same mode of develop- 

 ment as those of the blood- 

 vascular system (fig. 294), 

 except that anastomoses are 

 rare in them, and its course 

 is more limited to the mutual 

 apposition of fusiform cells, or of cells furnished with three 

 principal processes. Observations are wanting with respect to 

 the larger trunks of this system, although it cannot be doubted, 

 that they follow exactly the same course as the blood-vessels. 

 Engel (1. c.) has lately treated of the lymphatic glandSj and 

 states, that they proceed from lymphatic vessels which throw 

 out buds and are much convoluted. 



Fig. 294. Capillaries from the tail of a Tadpole : a, completed capillaries ; b, cell- 

 nuclei, and remains of the contents of the original formative cells ; c, caecal process 

 of a vessel ; d, stellate formative cell, connected by three prolongations, with three 

 processes of pervious capillaries; e, blood-globules, still retaining some granular 

 contents ; x 350 diam. 



