CHLOHOSIS. 213 



a limitary membrane ; they are made up of a finely granular 

 protoplasm containing distinct nuclear structures. We find 

 either a single, round nucleus of considerable size, or from two 

 to five smaller ones of lustrous aspect. In form the white cor- 

 puscles vary, inasmuch as they are endowed with a high degree 

 of spontaneous contractility ; in dead blood, they are spherical. 

 Accordingly they are cells, which resemble in every respect the 

 corpuscular elements of embryonic tissue and of pus, from which 

 indeed they can hardly be distinguished by any anatomical 

 criteria. 



3. The elementary vesicles discovered by Zlmmermann^ cir- 

 cular, colourless bodies with indistinct outlines, which owing to 

 their small size and transparency are only to be detected under 

 very high powers, but which are occasionally present in 

 enormous numbers. 



1. Chlorosis. 



§ 176. The chlorotic dyscrasia is essentially characterised by 

 a falling-off in the number of all the above-named stractures. 

 Of all alike, so that the proportion of the red to the colourless 

 corpuscles is in no wise altered. The blood as a whole seems 

 thinner and more clear — one might almost say more watery 

 than usual ; on evaporation, the percentage amount of solid 

 residue is decidedly below the normal average ; all this however 

 is due, not to any increase in the amount of water, but to a 

 positive diminution in the number of cells. Where an organ 

 depends for its colour on the blood it contains, as e.(/. the mucous 

 membranes (conjunctiva) and certain parts of the skin — we 

 observe a peculiar paleness, wdiich has caused the name of 

 " green-sickness " to be given to the disease. 



The etiology of chlorosis is still involved in some doubt. So 

 much is certain, that the chlorotic dyscrasia does not depend 

 upon a premature destruction, upon an atrophy of blood-cor- 

 puscles, but upon an inadequate sujDply of young and vigorous 

 elements to take the place of those which have completed their 

 term of existence, and are only fit to be cast out. But beyond 

 this, we cannot tell whether a functional disturbance of the 

 organs of sanguification (the spleen and lymphatic glands) or 

 some disorder of the more remote factors in the process (e.r/. 

 chylification) is to blame. Virchow's view is deserving of 



