t04- :>'.,>j\,,v\^ . 



406 Analogy between Vegetables and Animals, 



^dj mor 



payi^fyessels, and of small oblong bodies called glands. The 



yessels are plentifully furnished with valves, which gives them 



a knotted appearance. The}^ arise from all the internal cavi- 



i;ies, from every part of the surface, and from every organ of 



the body. In their course, they invariably pass through one 



pr more of the absorbent glands ; and, uniting into larger and 



larger branches, they at length form one common trunk called 



,the thoracic duct; which pours its contents into a large vein, 



near the heart, and there mingles them with the general mass 



of blood. The absorbent glands consist of a number of small 



xells enveloped in a membranous covering, in which is de- 



^posited a somewhat viscid fluid. They are found to be most 



numerous in the higher classes of animals ; but in many of 



the lower classes they are totally wanting. The orifices of 



jail the absorbent vessels, both those which suck up the chyle 



jfrom the alimentary cavity, and are termed lacteals^ and those 



iwhich imbibe substances applied to the skin, and are called 



lymphatics, commence in what are denominated ampullulce, 



j^yhich are small oval vesicles, composed internally, like the 



cj^bsorbent glands, of minute cells, and containing within them 



^a fluid of a viscid nature. The function of absorption is not 



tjggnfined to the lacteals and to the lymphatic vessels. Ma- 



jendie has shown that it is likewise performed by the veins. 



(Th^t the lymphatics and the veins should exercise the same 



^f^inction is not remarkable; for they both possess the same 



^^tructure ; both arise in the same manner ; both are furnished 



^^ith valves ; both carry their fluids from branches to trunks ; 



„both absorb their contents on the same principle ; and both 



l^irculate them by the agency of the same power. The lym- 



gphatics, in fact, are nothing more than a subordinate system 



2^yeins. 



.uf^The process of absorption is carried on in plants as exten- 

 sively as it is in animals : it is performed, too, by similar 

 organs, and on a similar principle. The roots take in the 

 jaiutritive fluid of the soil in which they are placed, and 

 ^imoisture is plentifully absorbed by the stem and branches. 

 I ; When we examine a root, we find that all the delicate fibrils 

 . J {growing out of it are terminated by small oval-shaped bodies 

 j called spongioles. These spongioles resemble, in their structure 

 *..and their form, the ampuUulee and the glands attached to 

 -jthe absorbent system of the animal body. Like them, they 

 ♦..are composed of small cells, enclosed within a membrane, 

 Iwcontaining a viscid fluid. They likewise receive the open 

 if extremities of the capillary tubes, of which the radical fibrils 

 y principally consist, precisely in the same manner as the am- 

 puUulae receive the orifices of the lacteal ^nd the lymphatic 

 vessels. 



