CHAPTER LXXXII 



DISEASES OE THE CIRCULATORY SYSTEM 



General remarks — The blood — Blood puzzles — Anaemia and allied conditions — 

 Leukaemia — General dropsy — The heart — The vessels — The spleen— 

 The bone-marrow — References. 



GENERAL REMARKS. 



In this chapter we merely make a jew allusions to some points of 

 tropical importance with regard to the blood and the organs which 

 produce and circulate it. The subject is not merely a large one, but 

 is of great importance in the tropics, and our few remarks are merely 

 of an introductory nature. 



THE BLOOD. 



We in no way intend to enter at all fully into an important study 

 of the blood, which is to be found in detail in the special books 

 devoted to its elucidation; but we desire, in the briefest manner 

 possible, to present to the reader a few remarks which have a direct 

 bearing upon the various references which we have made from 

 time to time in the preceding chapters with regard to it. 



The Erythrocyte. 



In embryonic life the first sign of the blood cell is to be found in 

 those mesoblast cells of the vascular area which contain haemoglobin 

 and are called megaloblasts, and to these are added later similar 

 cells without haemoglobin and found in the liver. In post-embryonic 

 life these cells are found in the red marrow lying at the ends of long 

 bones and in flat bones, and normally do not appear in the circulating 

 blood, but are the parents of the normoblasts, which are commonly 

 found in the blood after mid-term of foetal life and in the red bone- 

 marrow of post-embryonic existence. 



These normoblasts, multiplying by mitosis, are the source of the 

 erythrocyte, which alone is the proper denizen of the circulating 

 blood. 



An erythrocyte, according to von Schilling-T organ, is saucer- 

 shaped, with a thickened edge, and consists of :■ — 



I. An ectoplasmic cell membrane, inside which lies the endoplasm, 

 of which the peripheral portion is condensed to form the endoplasmic 

 capsule, which is Weidenreich's cholesterin-lecithin membrane, inside 



1895 



