AGGLUTINATION OF COLOURLESS BLOOD-CORPUSCLES. 185 



colourless corpuscles move, and that indeed often with 

 such constancy, that Weber came to the conclusion that 

 every capillary lay within a lymphatic vessel, in the inside 

 of which the colourless blood- or lymph-corpuscles 

 floated. But there cannot be the least doubt but that 

 the canals in question are single ones, in which 

 the colourless corpuscles float along closer to 

 the walls than the red ones ; and it is in this 

 peripheral space that, whilst the corpuscles 

 move on, we see one here and there stick fast 

 for a moment, then tear itself away and again 

 move on slowly, so that the name of the slug- 

 gish layer (tr'age Schicht), applied to this part 

 of the stream, has been universally adopted. 



These two peculiarities, first, that, when the 

 current becomes weaker, the corpuscles here and there 

 cling to the walls of the vessel, and in some measure 

 adhere to them, and, secondly, that they gather together 

 and become conglomerated into largish masses, combine 

 to produce this effect, that, when there exists a large 

 number of colourless corpuscles in the blood, and death 

 occurs, as it does in ordinary cases, after a gradual 

 weakening of the propelling force, the colourless cor- 

 puscles collect in vessels of every description, into small 

 heaps, and generally lie upon the outside of the later 

 formed blood-clot. 



If, for example, we pull out of the pulmonary artery 

 the generally very tough clot of blood which fills it, 

 minute granules will perchance be found upon its surface 

 (Fig. 58, A), little beads of a white colour, which look 

 like specks of pus, or are connected several of them toge- 

 ther in the form of a string of pearls. This appearance 



Fig. 59. Capillary vessel from the web of a frog's foot. r. The central stream 

 of red corpuscles. /, /, I. The sluggish, peripheral layer of the stream with the 

 colourless corpuscles. Magnified 280 diameters. 



