22 



SECOND LECTURE. 



thing. In evaporating blood it becomes indented (Fig. 

 28, b). Rapidly dried, it presents the appearance of c. On 

 the addicioii of water, the cell becomes globular and loses its 

 color. The coloring material, an extremely complicated sub- 

 stance, called haemoglobin, has now become dissolved. 

 Something similar is also seen in previously frozen blood. 

 The colorless residue is called stroma. 



A series of reagents, which have been applied to our 

 structures during many years, act similarly, some distending, 

 others shrinking ; but by no treatment does a nucleus make 

 its appearance. The human red blood corpuscle is, therefore, 

 a non-nucleated cell. 



Has the thing a membrane — does it possess a covering ? 

 we ask further. We answer negatively. An interesting ex- 

 periment is here, according to our opinion, decisive. When 

 living blood cells are warmed to 52 C, they commence a 

 marvelous transformation. Indentations of the border rapidly 



Fig. 29. — Colored blood cells ; i, from man ; 2, camel ; 3, pigeon ; 4, proteus ; 5, water salaman- 

 der ; 6, frog ; 7, cobitis ; 8, ammoccetes. At a, surface view ; b, profile (mostly after Wagner). 



occur, and partial constrictions of the cell body rapidly follow, 

 which either immediately break off or remain in connection 



