18 



THE COLOURLESS BLOOD-CORPUSCLES. 



to thirteen /u, and as a rule they are about 



an inch in diameter, 

 and in the smallest 

 the layer of the pro- 

 toplasm is extremely 

 thin. They all have 

 the property of ex- 

 hibiting amoeboid 

 movements which are 

 very apparent in the 

 larger corpuscles. 



These movements were 

 discovered by Wharton 

 Jones in the skate, and 

 by Davine in the cor- 

 puscles of man. Max 

 Schultze describes 

 three different forms 

 in human blood : 



Fig. 6. 



(1.) The smallest, 

 round forms, less than 

 the red corpuscles, with 

 one to two nuclei, and 



White blood-corpuscles A, Human, without the addi- 

 tion of any reagent. B, after the addition of 

 water, nuclei visible. C, after the action of acetic 

 acid. D, Frog's corpuscles showing changes of 

 shape due to amoeboid movement. E, Fibrils of a verv sma u amoun t O f 

 fibrin from coagulated blood. F, Elementary 

 granules. protoplasm; 



(2.) Round forms, 

 the same size as the coloured blood-corpuscles ; 



(3.) The large amoeboid corpuscles, with much protoplasm and 

 distinctly evident movements. 



[When a drop of human blood is examined under the microscope, 

 more especially after the coloured blood-corpuscles have run into 

 rouleaux, the colourless corpuscles may readily be detected, there 

 being usually three or four of them visible in the field at once. 

 They adhere to the glass slide, for if the cover-glass be moved, the 

 coloured corpuscles readily glide over each other, while the colourless 

 can be seen still adhering to the slide. 



White Corpuscles of Newt's. Blood. The characters of the colourless 

 corpuscles are best studied in a drop of newt's blood. Cut off the tip 

 of the tail and express a drop of blood on to a slide, cover it with a 

 thin glass, and examine. 



Neglecting the coloured corpuscles, search for the colourless, of which 

 there are three varieties : 



(1.) The Large Finely Granular Corpuscle, which is about -^ of an 



