214 MOREID STATES OP THE ELOOD, ETC. 



especial notice ; he finds that the aplastic state of the blood is 

 associated with a certain aplastic condition of the circulatory 

 apparatus as a whole, sc. the heart and arterial system (see 

 below), so that chlorosis would have to be viewed as a con- 

 genital, and not, as is generally held, an acquired disease. 



2. Leukli 



icemia. 



§ 177. The leukhasmic dyscrasia depends upon an alteration 

 in the numerical proportion of the Avhite to the red blood- 

 corpuscles. "We have already given 1 to 450 as the average 

 ratio of white to red corpuscles. A moderate increase in the 

 number of the colourless cells is consistent witli health and may 

 be demonstrated e.g. after every full meal. But if the number 

 of the white corpuscles undergoes so marked an increase in pro- 

 portion to that of the red ones, that we find e.r/. one wdiite to ten 

 red elements, or even an equal number of both, then indeed the 

 condition becomes manifest even to the unaided eye as a 

 decolorisation of the blood ; the blood assumes a paler, raspberry- 

 like hue, and w^e are thus entitled to speak of ^' white blood " or 

 leukh^emia. This most interestino; morbid state was described 

 in 1845 by Vircliow and Bennett simultaneously ; the German 

 pathologist however deserves the credit of having from the first 

 recognised and explained its real meaning. According to him, 

 we have to do w^tli an increased supply of colourless corpuscles 

 to the blood, due to a morbid state of those very organs -vvhicli 

 normally supply the blood with its colourless elements, viz. the 

 spleen and the lymphatic glands. 



§ 178. The SPLEEN has long been held to play an important 

 part in the renewal of the blood ; in our time it has been 

 regarded, now" as the grave of the red corpuscles, now as the 

 birthplace of the white ones ; KdlUker has justly attributed both 

 of these functions to it. Tlie excess of colourless cells in the blood of 

 the splenic vein is an indisputable fact ; they are from fixe to ten 

 times as numerous as in arterial blood. It is equally certain 

 that the lymphatic glands, particularly those of the mesentery, 

 are a source of white corpuscles. If we compare the lymph of 

 the thoracic duct with that of the peripheral lymphatics before 

 they enter the glands, we find that the former contains a far 

 larger proportion of lymph-corpuscles. The afflux of leucocytes 



