BLOOD igi 



glass, it is seen to consist chiefly of biconcave discs, and of those in the form 

 of shallow saucers (Fig. 182). They have a remarkable tendency to pile 

 up in rouleaux, like rolls of coins. It is said that discs of cork weighted 

 so that they will float beneath the surface of water, will come together in 

 a similar way if their surfaces have been coated with an oily substance. 

 If the blood coagulates, filaments of fibrin will be seen in the plasma, 

 as shown in the figure. In fresh specimens there is no fibrin, and within 

 the blood vessels it does not form under normal conditions. Moreover 

 when they are within the endothelial tubes, red corpuscles do not come 

 together in rouleaux. It is evident that the thin film of blood, though 

 very fresh, is examined under extremely artificial conditions; and from 

 such preparations, conclusions as to the normal shape of the corpuscles 

 should not be hastily drawn. Within the blood vessels the red cor- 

 puscles are typically cup-shaped. 



Rindfleisch (Arch. f. mikr. Anat., 1880, vol. 17, pp. 21-42) found that the corpuscles 

 in guinea-pig embryos, after losing their nuclei by extrusion, are at first bell-shaped; 

 but he considered that afterward they become biconcave discs from impact with others 

 in the circulating blood. Commenting upon this statement, Howell (Journ. of Morph., 

 1890, vol. 4, pp. 57-116) writes: 



"I feel convinced that the bell shape which Rindfleisch ascribes to the corpuscles 

 which have just lost their nuclei is a mistake. The red corpuscles even of the circula- 

 tion, as is well known, frequently take this shape when treated with reagents of any 

 kind, or even when examined without the addition of any liquid. It seems very 

 natural to suppose that the biconcavity of the mammalian corpuscle is directly caused 

 by the loss of the nucleus from its interior. Certainly as long as the corpuscles retain 

 their nuclei, they are more or less spherical, and after they lose their nuclei they become 

 biconcave." 



In the year preceding Howell's publication, Dekhuyzen discussed cup-shaped cor- 

 puscles (Becherfb'rmige rote Blutkorperchen, Anat. Anz., 1899, vol. 15, pp. 206-212) 

 which he found as a transient stage in mammals, and which his assistant saw in blood 

 drawn from his finger. Dujardin (Manuel de 1'observateur au microscope, 1842) 

 found many corpuscles shaped "like cups, or cupules (acorn cups) with thick borders" 

 in blood altered by the action of phosphate of soda. The first reference to such forms 

 is by Leeuwenhoek (1717) who put a drop of blood in a concoction of pareira brava, 

 and found that most of the globules which make the blood red, have "a certain bend 

 or sinus receding within, as if we had a vesicle full of water and by pressure of the finger 

 should hollow out the middle of the vesicle as a pit or depression." Von Ebner, in 

 Koelliker's Handbuch (1902), writes of bell or cap-shaped corpuscles produced in 

 warmed blood by the thickening of the border on one surface of the disc. Weidenreich 

 in 1902 (Arch. f. mikr. Anat.. vol. 61, pp. 459-507) after thorough study of blood 

 variously preserved, and also examined while circulating in the mesentery of a rabbit, 

 concluded that "the red corpuscles of mammals have the form of bells (Glocken)." 

 Weidenreich's conclusion has not been fully accepted by Jolly, David, Jordan, and 

 Schafer. Schafer (in Quain's Anat., vol. 2, 1912) states that " this opinion, although 

 shared by F. T. Lewis, Radasch and a few other histologists, cannot be accepted, for, 

 of examining the circulating blood in the mesentery and other transparent parts 

 in mammals, it is easy to observe that, with few exceptions, the erythrocytes, are 

 biconcave; this shape must' therefore be regarded as the normal one." 



