256 [Recess, 



will be seen to possess the power of adhering to each other in groups 

 and rows ; and on a closer examination the cohering parts will be 

 observed to have undergone a mutual flattening, just as in the case 

 of the corpuscles and bubbles before mentioned. 



We find then that the blood-corpuscles, while beneath the surface 

 of the serum, adhere to each other, sometimes by their biconcave 

 surfaces, so as to form rouleaux, sometimes by their peripheries, and 

 sometimes in both ways simultaneously. They adhere also to foreign 

 substances with which they come in contact, and on which they rest ; 

 and then currents in the liquor sanguinis give rise to tail-like pro- 

 cesses. An adherent mass of corpuscles is capable of being elon- 

 gated, and frequently gives way in the centre, when the two parts 

 recede into their respective masses. 



These effects occur contemporaneously with changes in the liquor 

 sanguinis. In the normal state of this liquid, the corpuscles have 

 no tendency to cohere j but the slightest modification of it, even 

 while within the vessels, confers cohesive power on the white cor- 

 puscle ; and the further alteration which occurs in blood taken from 

 the body disposes the red disks to arrange themselves in rouleaux. 

 When the liquor sanguinis is further altered by the addition of colloid 

 substances, or allowed to modify itself spontaneously, the corpuscles 

 become less elastic, and evince a great tendency to float with their 

 surface upwards, and hence to cohere by their edges. 



The attraction being proportionate to the amount of surface in 

 contact, when the disks are free to move in the vertical position, and 

 the tendency to cohesion is but moderate, they arrange themselves 

 by their plane surfaces as the cork-disks do, not because the edges of 

 the disks have no attraction for each other, but the planes offering 

 a larger surface of attraction, this position is not so easily disturbed 

 by currents in the serum. That this is the fact may be learned 

 from the circumstance that when the plane surface of a cork- or 

 blood- disk comes in contact with the side of a rouleau, it becomes as 

 firmly fixed as if applied to the plane of its fellow. Every specimen 

 of blood offers numerous instances of this kind. 



These then being some of the peculiarities of blood-corpuscles, we 

 learn, on the other hand, that globules of homogeneous liquids 

 attract and become incorporated with each other when submerged in 

 other liquids, being, like the blood-corpuscles, influenced in this 



