38 GENERAL ANATOMY. 



with the lymph and poured into the circulation through the same channels. It 

 must be borne in mind that these two sets of vessels, lymphatics and lacteals, 

 though differing in name, are identical in structure, and that the character of the 

 fluid they convey is different only while digestion is going on. At other times the 

 lacteals convey a transparent, nearly colorless fluid not to be distinguished from 

 lymph. Both these sets of vessels, in their passage to the central duct, pass 

 through certain small glandular bodies, termed lymphatic glands, where their 

 contents perhaps undergo elaboration. 



Lymph, as its name implies, is a watery fluid. It closely resembles the liquor 

 sanguinis, and contains about 5 per cent, of albumen and 1 per cent, of salts. 

 When examined under the microscope, it is found to consist of a clear colorless 

 fluid, in which are floating a number of corpuscles, lymph-corpuscles. These 

 bodies are identical in structure, and not to be distinguished from the white blood- 

 corpuscles previously described. They vary in number in different parts of the 

 lymphatic vessels, and indeed are said by Kblliker to be absent in the smaller 

 ones. They are always increased in number after the passage of the lymph 

 through a lymphatic gland, and are said to be increased in size as the fluid 

 ascends higher in the course of the circulation. 



Chyle is a milk-white fluid, which exactly resembles lymph in its physical and 

 chemical properties, except that it has, in addition to the other constituents of 

 lymph, an enormous amount of fatty granules, " the molecular basis of chyle," and 

 it is to the presence of these molecules that chyle owes its milky color. Under 

 the microscope it presents a number of corpuscles, named "chyle-corpuscles," 

 which are indistinguishable from lymph-corpuscles or white blood-cells, and the 

 molecular basis, consisting principally of fatty granules of extreme minuteness 

 (Fig. 5, a), but also of a few small oil-globules. Lymph and chyle after their pas- 

 sage through their respective glands, if withdrawn 

 from the body and allowed to stand, separate more 

 or less completely into a clear liquid, which is 

 identical with the serum of the blood, and a thin 

 jelly-like clot, consisting of a fibrillated matrix in 

 which lymph-corpuscles or chyle-corpuscles and 

 fatty molecules, as the case may be, are entangled. 

 If the contents of the thoracic duct are exam- 

 ined, especially after a meal, there may be found 

 in it corpuscles with a reddish tinge. These have 

 been regarded, probably erroneously, as immature 

 re( ^ corpuscles, or lymph- and chyle-corpuscles 



^^c;;, ;:;::; ;f;^:S in process of transformation into blood-globules. 

 FIG. 5.-chyie from the lacteals. They frequently give to the surface of clotted 



chyle and lymph a pinkish hue. They must not 



be mistaken for mature blood-globules, which are sometimes found in lymph and 

 chyle, and which are regarded by most observers as accidental i. e. produced by 

 the manipulations of the dissector. 



THE ANIMAL CELL. 



All the tissues and organs of which the body is composed were originally 

 developed from a microscopic body (the ovum), consisting of a soft gelatinous 

 granular material enclosed in a membrane, and containing a vesicle, or small 

 spherical body, inside which are one or more solid spots (see Fig. 73). This may 

 be regarded as a perfect cell. Moreover, all the solid tissues can be shown to con- 

 sist largely of similar bodies, differing, it is true, in external form, but essentially 

 similar to an ovum. These are also cells. 



In the higher organisms all such cells may be defined as '.' nucleated masses of 

 protoplasm of microscopic size." The two essentials, therefore, of an animal cell 

 in the higher organisms are, the presence of a soft gelatinous granular material, 



