1894.] 3IICR0SC0PICAL JOURNAL. 311 



puscles are moving. This is said to be because of their 

 less specific gravity, for in 1868, Schklarewsley showed 

 by physical experiments, that particles of least specific 

 gravity, in glass capillaries, are pressed toward the wall, 

 while the ones of greater specific gravity, remain in the 

 center of the stream. 



In the smallest capillaries the red corpuscles move 

 along in single file, sometimes being compressed be- 

 tween the walls but regaining their former shape, on ac- 

 count of their elasticity, on reaching larger vessels. The 

 white corpuscles are plainly seen, rolling along, sticking 

 here and there on the vessel wall and sometimes being 

 swept off" again by the axial current. 



First. After a leucocyte has remained for a variable 

 length of time upon the vessel wall, and just before it 

 can be seen to send a process into it, the granules, which 

 I stated as being distributed throughout it, all seem to 

 be in njiotion and congregate thickly at that portion of 

 the leucocyte lying furthest from the vessel wall or in 

 other words, nearest the axial stream of the vessel. 



Second. The leucocyte next sends off a process, which 

 is almost exactly the same as that which every other leu- 

 cocyte sends off, in its general outline, and this process 

 is entirely free from pure protoplasm. This process 

 seems to gradually push or work its way through the 

 wall. 



Third. Now occurs a most singular thing. As the 

 vessel wall at last gives way and the process of the leu- 

 cocyte emerges upon the outer side of the vessel, the 

 granules, which have, during the penetration of the wall, 

 congregated at the furthest part of the leucocyte from 

 the wall, — these granules fly swiftly through the passage 

 thus made in the vessel wall by the protoplasm of the 

 cell, from the interior of the vessel to the furthest point 

 of the process outside the wall, leaving the part of the 

 leucocyte not yet through the wall, free from granules. 



