80 HAND-BOOK OF PHYSIOLOGY. 



the full-sized varieties, a number of smaller corpuscles, consisting of a 

 large spherical nucleus surrounded by a variable amount of more or less 

 granular protoplasm. The small corpuscles are, in all probability, the 

 undeveloped forms of the others, and are derived from the cells of the 

 lymph. Besides the above-mentioned varieties, Schmidt describes another 

 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 cor- 

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

 cold-blooded animals. 



Amoeboid movement. A remarkable property of the colorless cor- 

 puscles consists in their capability of spontaneously changing their shape. 

 This 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 mois- 

 ture is prevented, and at the same time the temperature is maintained at 

 about that of the blood in its natural state within the walls of the living 

 vessels, 100 F. (37 "8 C.), the colorless corpuscles will be observed slowly 

 altering their shapes, and sending out processes at various parts of their 

 circumference. This alteration of shape, which can be most conveniently 



FIG. 78. Human colorless blood-corpuscle, showing its successive changes of outline within 

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



studied in the newt's blood, is called amoeboid, inasmuch as it strongly 

 resembles the movement of the lowly organized amccba. The processes 

 which are sent out are either lengthened or withdrawn.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 and the corpuscle changes its position; if withdrawn, protrusion of 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 circumference 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 compar- 

 atively 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 containing from five to twenty nuclei. Another 

 phenomenon may be observed in such a specimen of blood, viz., the divi- 

 sion of the corpuscles, which occurs in the following way. A cleft takes 

 place in the protoplasm at one point, which becomes deeper and deeper, 



