COLOURLESS CORPUSCLES OF THE BLOOD. 



nucleus with but little surrounding protoplasm. They seem to be young forms of 

 the more protoplasmic corpuscles, and are perhaps identical with the lymphoid cells 

 formed in lymphatic glands and similar structures. 



The corpuscles often have one or more conspicuous vacuoles in their protoplasm, 

 but these are inconstant, and may appear and disappear in the same corpuscle. 

 Sometimes they are filled with small vacuoles so that the cell-substance assumes a 

 frothy aspect. This is commoner in the white blood-corpuscles of the newt and 

 other cold-blooded animals than in those of man. By means of the amoeboid 

 movement of their protoplasm, the pale corpuscles, under some circumstances, 

 possess the power of wandering or emigrating from the blood-vessels, penetrating 

 between the elements of their coats, and in this manner they find their way into the 

 interstices of the tissues, and hence into the commencements of the lymphatics. 

 Cells like these which appear to be wandering independently in the tissues, and 

 particularly in the connective tissue, are known as migratory or wander-cells. 



Besides the two forms of pale corpuscles above referred to, others have been described 

 which differ from them in containing red-coloured granules in their protoplasm. According 

 to A. Schmidt and Semmer, such cells are very numerous in the circulating blood, but on 

 withdrawal of the blood from the vessels they become rapidly destroyed and disappear without 

 leaving a trace. Schmidt looks upon them as transitional forms between the white and red 

 corpuscles, but the evidence of their constant occurrence in normal blood is at present 

 unsatisfactory. 



The pale corpuscles possess polar particles with well-marked attraction-spheres 

 (Flemming), and one, two, or more nuclei, Avhich are generally obscure in 

 the living condition, but are sometimes clearly seen when the corpuscle becomes 

 flattened out, and may always be brought into view by reagents. The nuclei are 

 apt to take on peculiar shapes, caused perhaps by traction 

 exercised upon them by the movements of the surrounding 

 protoplasm. Thus a nucleus not unfrequently becomes 

 elongated and either irregular in outline (fig. 249) or folded 

 on itself, so that when the ends are turned up, the appear- 

 ance of two nuclei is produced, where in reality there 

 may be but one. In fact the occurrence of several nuclei 



Fig. 249. A PALE CORPUSCLE i n tne P a ^ e corpuscle is much more rare than is generally 

 OF THE SALAMANDER, SHOW- supposed, for it will be usually found that even when 

 ING ELONGATED IRREGULAR there appear to be several nuclei in a corpuscle they are 



NUCLEUS WITH INTHANU- . , f , . , , J 



CLEAR NETWORK. (Flem- united together by long strands of cnromoplasm (ng. 247, 

 min g- ) J, c). In other respects they have the normal structure and 



appearance of cell-nuclei, containing the usual network. 



The division of the nucleus and of the corpuscles takes place by karyokinesis in the 

 same way as in other animal cells. It has been observed in the lymph-cells of 

 lymphoid tissue which afterwards become the pale corpuscles of lymph and blood, 

 and also in some instances in corpuscles within the blood itself. 



Action of reagents. Water swells up and destroys the protoplasm of the white corpuscles, 

 setting free the granules. If but little water be mixed with the drop of blood, the protoplasm 

 may not be destroyed, but the corpuscles are swollen out (fig. 250, 1), and the granules take on 

 an active Brownian movement. Acetic acid causes a granular precipitate in the protoplasm, 

 the granules collecting around the nucleus, which is brought very strongly into view (fig. 250. 

 2, 3). A clear bleb-like swelling is also generally produced from one or more sides of the 

 corpuscle ; but this appearance is not peculiar to acids, for it is often seen as an accompani- 

 ment of the death of the corpuscle, whether as the result of the action of reagents or from 

 other causes. If produced by a solution of iodine, the bleb sometimes becomes coloured of a 

 faint port-wine tint, a reaction which is generally taken as an indication of the presence of 

 glycogen. 



In the blood of the splenic vein, and also in the pulp of the spleen itself, cells have been 

 noticed resembling pale corpuscles in their structure, but much larger, and enclosing in their 



