THE RED PARTICLES. 277 



is surrounded by a vesicle. We may conjecture with a great 

 degree of probability, that the vesicle is either a secretion from 

 the internal coat of the lymphatic vessel, or that the lymphatic 

 vessel has a plastic power over its contained fluid, so as not 

 only to form a vesicle round the central particle, but also to 

 give it its red colour, for till the red vesicle is formed, the 

 central particle is evidently white. 



SECT. 86. That a lymphatic vessel, after it has passed through 

 a lymphatic gland, contains lymph, red blood, and central par- 

 ticles, will not admit of a doubt to any one who will take the 

 trouble of making the experiment. How then are these red 

 particles formed, if not by the lymphatic vessels ? 



SECT. 87. In Chap. II, sect. 19, we prove that central particles 

 are formed in the lymphatic glands; and from our finding 

 them presently afterwards taking on their vesicular portions 

 in the lymphatic vessels or being completely made, we cannot 

 doubt but that the lymphatic vessel gives them the red vesicle; 

 but in what manner this is performed, whether by a secretion 

 from the internal coat of the vessel, or by a plastic power of 

 the vessel itself over its contained fluid, is perhaps a circum- 

 stance among the arcana of nature too minute for human in- 

 vestigation. 



SECT. 88. And it is amply sufficient to our purpose to prove 

 that the lymphatic vessels and glands are of themselves capable 

 of forming the red part of the blood. 



SECT. 89. It will probably be asked, if the lymphatic glands 

 are given to form the central particles, how are those particles 



generally found to be smaller, more irregular and less perfect in 

 shape, than the red corpuscles in the blood ; and the same observation 

 is applicable to the red corpuscles in the splenic lymph of this animal. 

 Dr. Simon's observations* on red corpuscles in the thoracic duct of 

 the rabbit and horse, are to. the sa'me effect. Schultz and Gurlt b also 

 noticed the chyle of a reddish colour from the presence of blood-cor- 

 puscles, of which they suppose, with Simon, the formation to begin in 

 the chyle. The transition of the corpuscle of the chyle or lymph into 

 the red corpuscle of the blood seems now to be commonly admitted in 

 Germany : see Note cxxn, pp. 253-4. Dr. Davy informs me that he 

 found a small portion of red crassamentum in the thoracic duct of a 

 man who died suddenly of apoplexy. 



a Animal Chemistry, tr. for the Syd. Soc. b Muller's Physiology, tr. by Dr. Baly, 

 vol. i, pp. 120-21, 8vo, Lond. 1845. vol. i, p. 563. 1st edit. 



