THE BLOOD AND THE LYMPH. 699 



the Mouse, the Rat, and, to some extent, of the Rabbit, a complete 

 muscular layer. In the Bat also, the Dog, Sheep, Ox, Goose, and 

 Fowl, smooth muscles are said to occur sparingly, and to be fewest in 

 Man. Heyfelder also says that they pass into the internal .septa, and 

 that in the Rabbit he has noticed contractions of the glands upon 

 electrical excitement, an experiment which has not yet succeeded 

 with me. 



The lymphatic glands are subject to numerous degenerations. The 

 most frequent are extravasations of blood in the alveoli, and in conse- 

 quence of these effusions, depositions of pigmentary matter, which may 

 proceed to such an extent as to render the glands brownish-red, or even 

 black (bronchial glands) ; we also find thickenings of the sheath, and 

 of the internal septa ; fatty deposits in the bloodvessels ; hypertrophies, 

 with a uniform increase of all their parts ; tuberculosis and cancer.* 



4. OF THE BLOOD AND THE LYMPH. 



220. Every part of the vascular system contains in its interior a special 

 liquid, consisting of a fluid and numerous morphological particles, and 

 which, according to its color, its occurrence in one or other division of 

 the system, and its other properties, is distinguishable on the one side 

 into white and red blood, and lymph or chyle ; and on the other, into 

 blood in the more strict sense of the term. Histology is concerned only 

 with the description of the morphological elements existing in these 



* [Professor Brttcke, in a valuable communication read before the Vienna Academy, 

 March 31, 1853 (" Ueber'die Cbylus-gefasse und die Fortbewegung der Chylus"), confirms 

 the account given by Ludwig and Noll of the structure of the lymphatic glands, and states 

 that the vasa inferentia break up into the porous, glandular tissue, out of which the vasa 

 efferentia arise anew. In the glands themselves, a distinction must be drawn between the 

 cortical substance, composed of round or ovate bodies, like the separate glandular bodies of 

 Peyer's patches, and the medullary substance. The framework of the latter is formed by the 

 large bloodvessels, with their tunica adventitia. One portion of their branches divides into 

 capillaries in the medullary substance, the rest enter the cortical substance. The accom- 

 panying connective tissue becomes looser, the finer the branches. The fully developed 

 connective fibres disappear more and more, and in their place cytoblasts appear, with closely 

 investing^cell-membranes, which run out into two or three pointed, sometimes flat, usually 

 filiform processes, fitted together into a soft tissue, in which the capillaries of the medullary 

 substance lie. Round cells in different stages of development follow them, resembling the 

 lymph-corpuscles, and forming the immediate limit of the fine, irregular, frequently anasto- 

 mosing canals, which render the medullary substance as porous as a sponge. The whole 

 gland is enclosed in a membrane, which, as Heyfelder observed, is composed of connective 

 tissue and smooth fibre-cells, and sends sheaths in towards the medullary substance, whereby 

 imperfect compartments are formed, in which the glandular elements lie. The chyle of the 

 vasa inferentia traverses the glandular elements, enters the pores of the medullary substance, 

 and passes thence on the opposite side, between the glandular elements to the vasa inferentia. 

 " I have never," (says Briicke) "observed the fat-drops of the chyle enter into the interior of 

 the glandular elements, which appear to be merely bathed with the fluid part of it. On the 

 other hand, the cells which are formed in the glandular elements pass as lymph-corpuscles 

 into the chyle." TRS.] 



