GENERAL VIEW OF THE ANIMAL FUNCTIONS. 97 



into the blood again, in part, directly, through the walls of the capil- 

 laries and finest veins, but also, and chiefly, through the general 

 absorbent vessels, which resemble the lacteals already mentioned, but 

 which are named lymphatics, because they here carry a clear fluid or 

 lymph. Should accident or disease still further impair the integrity 

 of an organ by bruising, cutting, or by inflammatory processes, the 

 nutritive function is exercised, in a special manner, for the reparation 

 of the injured part, and sometimes even for the restoration or repro- 

 duction of lost parts. Nutrition includes, therefore, the processes or 

 functions of reparation and local reproduction. Lastly, parts which 

 are destined to be removed, such as the fangs of the milk teeth, and 

 the materials of the growing bones ; or morbid deposits, such as blood 

 which has escaped from the vessels into the tissues ; and inflammatory 

 products, are likewise absorbed back into the blood, by the act of 

 nutritive absorption, which is performed jointly by the capillaries and 

 the lymphatics. 



But, besides all this, there is included in the nutritive function, the 

 conveyance of a so-called stimulating substance to those two remark- 

 able tissues of the animal body, the muscular and the nervous tissues, 

 both of which require, for the performance of their proper functions, 

 not only new material to replace that which is destroyed or disinte- 

 grated by use, but likewise the presence of arterial blood, for the main- 

 tenance of their peculiar vital endowments : such blood operates chiefly 

 by virtue of the large quantity of oxygen which it contains. In supply- 

 ing the requisite materials for the nutrition and stimulation of the 

 tissues, all of which have their characteristic chemical composition, in 

 receiving back the residual nutrient substance, and in furnishing the 

 materials for another important nutritive function, named secretion, to 

 be presently described, the blood itself becomes not only exhausted as 

 regards the quantity of its ingredients, but necessarily modified as re- 

 gards their quality ; and hence certain special elaborative processes 

 are continually going on, for the purpose of securing its own nutri- 

 tion ; these constitute the functions of sanguification. This is accom- 

 plished partly by the absorption of new matter entering through the 

 lacteals and the absorbent glands, already mentioned, and also it is 

 believed by the agency of certain organs named vascular glands or 

 blood glands, such as the spleen, the supra-renal bodies, the thyroid 

 body, and the thymus gland, and the so-called Peyer's glands and 

 solitary glands of the intestinal canal, all of which appear to assist in 

 the elaboration of special materials for the blood. 



We have seen that in order to render the nutrient substances con- 

 tained in the food soluble, and fitted for absorption, certain animal 

 fluids or juices are employed in the process of digestion, such as saliva, 

 gastric juice, bile, pancreatic fluid, and the intestinal juice. These 

 special fluids require each a special organ in the body for its prepara- 

 tion, named a gland. Moreover, they are prepared within these 

 glands, from the fluid plasma of the blood poured out through the 

 coats of the capillaries. The general process by which they are thus 

 separated from the blood, is known as secretion, and the glands are 

 called secreting glands. The process of secretion is closely allied to 



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