74 



cytes may be seen in the peripheral zone, if the current is not 

 too rapid ; in that of the veins a few leucocytes and occasion- 

 ally a red one will be seen moving along comparatively slowly. 



282. Note the passage of the corpuscles usually in single 

 file through the capillaries. 



283. Note the elasticity of the red corpuscles, observing 

 the way in which they bend and later regain their normal form. 



284. Study of inflammatory conditions. Remove the 

 cover-glass and absorb the fluid on the web ; touch the middle 

 of the web with the tip of a glass rod that has been dipped in 

 creosote (or a 2% solution of croton oil in olive oil) leaving a 

 minute drop on the web. Put on a cover-glass as before and 

 examine with the microscope. If not successful with the web, 

 try the tongue or mesentery. 



285. Note the dilation of the arteries, the more distinct 

 appearance of the capillaries, and the enlargement of the veins, 

 accompanied by a quickening of the current. 



286. Note a little later, the slowing of the current, the 

 vessels remaining dilated. 



287. Note that the leucocytes increase in number in the 

 peripheral zone of both arteries and veins ; in the latter the 

 leucocytes begin to cling to the sides, temporarily at first and 

 then permanently. In the capillaries the leucocytes and, less 

 frequently, the red corpuscles stick to the capillary walls, 

 partially or completely blocking the way. Later stagnation 

 may set in and there is then the appearance of the gradual 

 obliteration of the outlines of the corpuscles. 



288. Note the migration of the leucocytes from the capil- 

 laries and veins. This occurs when the circulation becomes 

 slow. Watch, at intervals of 10 minutes, some particular 

 leucocyte adhering to the wall of a capillary or vein. 



289. Note the diapedesis of the red corpuscles from the 

 capillaries, seen to the best advantage in those capillaries in 

 which the current has almost ceased. 



290. Note that the above effects are local, are of greatest 

 intensity in the spot touched, they extend some distance 

 around the spot, but the circulation in the rest of the web is 

 normal. If the injury has not been too severe, the circulation 

 may become re-established in the stagnated spots, and the 

 inflammatory appearances disappear. 



