164 



OF THE BLOOD. 



burst and discharge these granules, whose molecular movement still continues. 

 The Colorless corpuscles possess, moreover, a higher refracting power than the 

 red; from which they are further distinguished by their greater firmness, and by 

 the absence of any disposition to adhere to each other ; so that, when a drop of 

 recent blood is placed between two strips of glass, and these are gently moved 

 over one another, the white corpuscles may be at once recognized by their soli- 

 tariness, in the midst of the rows and irregular masses formed by the aggrega- 

 tion of the red. This is still better seen in inflammatory blood; in which the 

 Red corpuscles have a peculiar tendency to adhere to one another, whilst the 

 White are commonly present in unusual number. 



146. The Colorless corpuscles may be readily distinguished in the circulat- 

 ing Blood, in the capillaries of the Frog's foot ; and it is then observable that 

 they occupy the exterior of the current, where the motion of the fluid is slow, 

 whilst the red corpuscles move rapidly through the centre of the tube (Fig. 13). 

 The Colorless corpuscles, indeed, often show a disposition to adhere to the 

 walls of the vessels ; which is manifestly increased on the application of an 

 irritant. Hence the idea naturally arises, that (to use the words of Mr. Wharton 

 Jones) " there is some reciprocal relation between the colorless corpuscles, and 

 the parts outside the vessels, in the process of nutrition." Of the nature of 

 this relation we have no certain knowledge ; but if the Red corpuscles discharge 

 the function which has been suggested for them ( 142), of preparing the nu- 

 trient material for Muscle and Nerve, it may not be deemed improbable that 

 the Colorless corpuscles should perform a similar office for the other albuminous 

 tissues. A very remarkable spontaneous change of form has been observed by 

 Mr. Wharton Jones to take place in the Colorless corpuscles whilst being ex- 

 amined under the microscope; 1 and this 

 not only in the blood of Man, but in 

 that of animals of all the Vertebrated 

 classes, as also in that of Invertebrata, 

 whose only corpuscles are of this charac- 

 ter ( 147). From some point of their 

 circumference a protrusion of the cell- 

 wall takes place, the form of which seems 

 quite indefinite ; soon afterwards, another 

 protrusion may be seen to arise from ano- 

 ther part of the cell, the first being either 

 drawn in again, or remaining as it was; 

 and thus the configuration of the corpus- 

 cles may be seen to undergo several 

 changes before the process finally ceases, 

 and this whilst they are floating in their 

 own serum, and- the red corpuscles are 

 lying quite passive in their immediate 

 vicinity. These changes of form, which 

 bear a striking resemblance to those of the 

 Proteus-cell, already referred to ( 109), 

 are affirmed by Dr. Davaine (by whom 

 they have been more recently studied) to 

 be visible even whilst the blood is circu- 

 lating through the vessels, in those colorless corpuscles which are retarded by 

 attraction to their walls. 3 



147. The proportion which the White or Colorless corpuscles bear to the m 



A small venous trunk, a, from the Web-of the 

 Frogs foot, magnified 350 Diameters ; b, b, cells 

 of, pavement-epithelium, containing nuclei. In 

 the space between the current of oval Blood-cor- 

 puscles, and the walls of the vessel, the round 

 transparent white corpuscles are seen. 



1 "Philosophical Transactions," 1846, pp. 64, 71, 90, &c. 



2 "Memoires de la Societe de Biologic," torn, ii pp. 103-5. 



