THE BLOOD, 75 



form which he looks upon as intermediate between the colored and the 

 colorless forms, viz., certain corpuscles which contain red granules of 

 haemoglobin in their protoplasm. The different varieties of colorless 

 corpuscles are especially well seen in the blood of frogs, newts, and other 

 cold-blooded animals. 



Amoeboid movement. The remarkable property of the colorless 

 corpuscles of spontaneously changing their shape was first demonstrated 

 by Wharton Jones in the blood of the skate. If a drop of blood be 

 examined with a high power of the microscope on a warm stage, or, in 

 other words, under conditions by which loss of moisture is prevented, 

 and at the same time the temperature is maintained at about that of the 

 blood within the walls of the living vessels, 100 F. (37.8 0.), the- 

 colorless corpuscles will be observed slowly to alter their shapes, and to 

 send out processes at various parts of their circumference. The amoeboid 

 movement can be most conveniently studied in the newt's blood. The 

 processes which are sent out from the corpuscle are either lengthened or 

 withdrawn. If lengthened, the protoplasm of the whole corpuscle flows 

 as it were into its process, and the corpuscle changes its position; if 

 withdrawn, protrusion of another process at a different point of the cir- 



FIG. 75. Human colorless blood-corpuscle, showing its successive changes of outline within ten 

 minutes when kept moist on a warm stage. (.Schofield.) 



cumference speedily follows. The change of position of the corpuscle 

 can also take place by a flowing movement of the whole mass, and in 

 this case the locomotion is comparatively rapid. The activity both in 

 the processes of change of shape and also of change in position, is much 

 more marked in some corpuscles, viz., in the granular variety than in 

 others. Klein states that in the newt's blood the changes are especially 

 likely to occur in a variety of the colorless corpuscle, which consists of 

 masses of finely granular protoplasm with jagged outline, containing 

 three or four nuclei, or of large irregular masses of protoplasm contain- 

 ing from five to twenty nuclei. Another phenomenon may be observed 

 in such a specimen of blood, viz., the division of the corpuscles, which 

 occurs in the following way. A cleft takes place in the protoplasm at 

 one point, which becomes deeper and deeper, and then by the lengthen- 

 ing out and attenuation of the connection, and finally by its rupture, two 

 corpuscles result. The nuclei have previously undergone division. The 

 cells so formed are remarkably active in their movements. Thus we see 

 that the rounded form which the colorless corpuscles present in ordinary 

 microscopic specimens must be looked upon as the shape natural to a dead 

 corpuscle or to one whose vitality is dormant rather than as the shape 

 proper to one living and active. 



