316 ANATOMICAL TECHNOLOGY. 



§ 820. The Lymph Vascular System. — This is that part of the general vascular sys- 

 tem which collects the lymph from the tissues and the chyle from the alimentary canal 

 and conveys them to the great veins ; it is thus an auxiliary of the venous system (Bernard, 

 A, 350). From the office of collecting both lymph and chyle, it is commonly considered 

 as forming two divisions : (A) The lymphatics proper ; (B) the lacteals or chyle vessels. 



§ 821. The lymphatic system is somewhat comparable to the venous, since its vessels 

 begin as capillaries at the periphery and extend toward the center. Like the veins also, the 

 lymphatic vessels contain numerous valves which prevent a reversal of the current, that is, 

 a flow from the center toward the periphery. 



The lymphatic vessels difl'er from the veins in the following particulars : (A) They 

 have thinner walls ; (B) they do not so markedly increase in size as the veins, although 

 they anastomose more frequently ; (C) at various points along their course there are 

 enlargements, the so called lymphatic glands, through which the lymph passes; (D) in- 

 stead of joining the central organ of the vascular system directly as do the blood vessels, 

 the lymphatic trunks open into veins (Fig. 103) ; (E) the lymphatic system differs from 

 the venous also in having no direct communication through capillaries with anything like 

 an arterial system ; (F) the lymphatics are found to communicate with serous cavities 

 through minute orifices, the stomata (Quain, A, II, 188 ; Strieker, A, 232). 



CARDIA— THE HEART. 



§ 833. References.— Quain, A, II, 342 ; Gray, A, 801 ; Cuvier, A, VI, 273 ; Gegeubaur 

 (Lankester), A, 583 ; Hyrtl, A, 800 ; Bernard, A, 374 ; Milne-Edwards, A, III, 473 ; Owen, 

 A, III, 516 ; Chauveau, A, 529 ; Chauveau (Fleming), A, 499 ; Gurlt, A, 574 ; Straus- 

 Durckheim, B, II, 181 ; Foster and Langley, A, 91 ; Smith, E. N., A, PI. 47, 48, 49, 55, 56 ; 

 Bourgery and Jacob, A, Pi. 9, bis, PI. 13 ; Rolleston, B, 25-34 ; Mc Alpine, B, I, PI. 23; 

 Krause, A, 178, Fig. 13; Turner, A, 899 ; Sabatier, A ; Flower, A; Pettigrew, 64; Petti- 

 grew, A ; Parchappe, A ; Mojsisovics, A, 54 ; Leyh, A, 559 ; Mivart, B, 199-206. 



Remark. — Most of the above refer to the human heart more especially, but the heart 

 of the horse is chiefly described by Leyh, Chauveau and Gurlt, and that of the rabbit by 

 Krause, McAlpine and Foster and Langley. Methods of preparation are given by Hyrtl, 

 Straus-Durckheim, Mojsisovics and Pettigrew. The only descriptions and figures purport- 

 ing to refer to the heart of the cat are given by Mivart ; unfortunately, however, in Fig. 

 102, the relative thickness of the right and left ventricles is made the reverse of what it 

 should be (a probable oversight which, although readily corrected by the anatomist, is 

 sure to confuse the beginner) ; while the usefulness of the text is diminished both by the 

 general uncertainty as to how much refers directly to the cat (§ 127), and by the presence 

 of an absolute misstatement upon pp. 201, 214 respecting the number of pulmonary veins. 



§ 833. Before dissecting the heart, or even removing it from the body, the student will 

 do well to familiarize himself with its general features and location as shown in Fig. 77, 

 91, 101. 



If he has been following the present work in order, he will have at least one cephalic 

 region of a cat preserved in alcohol, and may run the risk of injuring the heart thereof in 

 removing it before gaining any detailed knowledge of it. He must bear in mind, how- 

 ever, that all the cavities of such a heart will be collapsed and that the auricles especially 

 -will look very unlike the preparation shown in Fig. 91 . Such a heart may serve for the 

 examination of some parts, but eventually he should have at least two specimens well dis- 

 tended and hardened by alcohol, and if possible another filled with plaster. 



§ 824. Preparation— Fig. 91. — ThQ postcava and abdominal aorta 



