SYSTEMATIC SYNTHESIS OF TISSUES. 195 



214. THE BLOOD-CELLS CONSTANTLY DISSOLVE, and 

 new ones take their place in rapid succession. It is 

 computed that not less than twenty millions of them die 

 every moment and yield their contents to the Blood, and 

 as many come into it in the same time. 



215. THE BLOOD-CELLS AKE OF TWO KINDS, red and 

 white, the latter about one tenth in number, and the 

 source of the former by means of appropriate changes. 



216. THE RED BLOOD-CELLS give color to the Blood, 

 and by their change in form affect its shades. 



217. THE FORM OF THE RED CELLS is AFFECTED by 

 the reception and discharge of carbonic acid, which is 

 received in the different parts of the Body from the de- 

 composing tissues, and darkens the color of the Blood ; 

 it is given off in the lungs, when the form of the cells 

 again changes and their color brightens. 



218. THE CELLS CONTAIN a semi-liquid substance of 

 an albuminous character, not definitely understood, 

 called Globuline, and a red coloring matter called Hae- 

 matine, in which the iron of the Blood is found ; and as 

 it is found in combination with other coloring matters, 

 and only with such in the Body, it is thought to be of 

 prime consequence in that respect. 



219. THE CELLS DOUBTLESS ARE floating plants that 

 prepare the constituents of the Blood for their higher 

 position in the tissues. 



220. IF THE CELLS ARE STRAINED OUT OF THE BLOOD, 



the remaining portion, if allowed to stand, will separate 

 into a fibrous mass called fibrin, or the clot, and a liquid 

 portion called the serum of the Blood. 



221. IF BLOOD BE DRAWN AND STIRRED WITH RODS, 

 fibres of the same substance will cling to them. 



222. IT is A QUESTION how or where this fibrin of the 

 Blood is formed and what end it serves. It has nearly 

 the same constitution as albumen. Most argue that it is 



214. How do ? 215. Of what ? 216. What the effect ? 21T. How is ? 

 218. Wliat do ? 219. What - f 220. What ? 221. What - ? 222. What 9 



