OF THE BLOOD AND CIRCULATION. 



211 



[ 37 4. A magnifying power of from two to three hundred 



diameters is required, to make out the particular details of the 



peripheral circulation. The blood in mass, or in the larger 



channels is seen to flow more rapidly than in the smaller. 

 the blood-corpuscles advance with great rapidity, espe- 

 cially in the arteries, and with a whirling motion, and form a 

 iy crowded stream in the middle of the vessel, without 



ever touching its parietes. 



AVith a little attention a 



narrower and clearer but 



always very distinct space 



is seen to remain betwixt 



the great middle current 



of blood-corpuscles and 



the bounding walls of the 



vessel, in which a^few of 



the lymph-corpuscles are 



moved onwards, but at a 

 slower rate (figs. 22S 



and229,c,a). Theseround 



lymph-corpuscles swim in 



smaller numbers in the 



transparent liquor san- 



guinis, and glide slowly, 



and in general smoothly, Fig. 228. A venous branch from the 



though sometimes they ad- web * of Rana temporana magnified 350 



vnnrp bv fits and starts times, running immediately under the sur- 

 face. The cells of the epidermis, 4, b, b, b, 

 flattened, mostly six-sided, connected 

 like a piece of pavement, and generally 

 provided with nuclei, are seen extended 

 over the vessel. The closely serried co- 

 lumn of blood-globules, some with their 

 edges, others with their broad faces 

 turned to the eye, is distinguished ; in 

 the clear space betwixt the blood-globules 

 and the parietes of the vessel, which ap- 

 pear made up of longitudinally disposed 

 parallel fibres, the round, clear, and more 

 slugglishly moving lymph-globules are ap- 

 parent. The object is represented under 

 a weak light. 



more rapidly, but with in- 

 tervening pauses, and, as a 

 general rule, at least from 

 ten to twelve times more 

 slowly than the corpuscles 

 of the central stream. The 

 clear space filled with li- 

 quor sanguinisand lymph- 

 corpuscles is obvious in all 

 the larger capillary vessels, 

 whether arterial or venous; 



but it ceases to be apparent 

 -mailer intermediate 



liich admit but one or two ranks of blood-corpuscles 



p 2 



