430 Dr. Norris on the Aggregation of Blood-corpuscles. [May 27, 



fact, many theories have been advanced to explain its nature ; but all of 

 them, without exception, have laboured under the disadvantage of being 

 purely hypothetical in their character, and quite incapable of demonstra- 

 tion by an appeal to experiment. Thus, while some writers have attri- 

 buted the effect to an imaginary law of vital attraction, others have more 

 correctly referred it to the operation of some unexplained physical cause. 



Professor Lister (son of the original observer already mentioned), who 

 has devoted much attention to this subject, says, in a paper submitted to 

 the Royal Society, June 18, 1857, and published in the Philosophical 

 Transactions for 1858, p. 648 : — " For my own part, I am satisfied that the 

 rouleaux are simply the result of the biconcave form of the red disks, to- 

 gether with a certain though not very great degree of adhesiveness, which 

 retains them pretty firmly attached together when in the position most 

 favourable for its operation, viz. when the margins of their concave 

 surfaces are applied accurately together, but allows them to slip upon one 

 another when in any other position. There is never to be seen anything 

 indicating the existence of an attractive force drawing the corpuscles 

 towards each other : they merely stick together when brought into contact 

 by accidental causes. Their adhesiveness does not affect themselves alone, 

 but other substances also, as may be seen when blood is in motion in an 

 extremely thin film between two plates of glass, when they may be observed 

 sticking for a longer or shorter time to one of the surfaces of the glass, each 

 one dragging behind it a short tail-like process." 



Again, at the end of section I., p. 652 of the same paper, Lister says, 

 " From the facts detailed in this section, it appears that the aggregation 

 of the corpuscles of blood removed from the body depends on their pos- 

 sessing a certain degree of mutual adhesiveness, which is much greater in 

 the colourless globules than in the red disks, and that in the latter this 

 property, though apparently not dependent upon vitality, is capable of 

 remarkable variations in consequence of very slight chemical changes in the 

 liquor sanguinis 



From these quotations it is apparent that Mr. Lister ignores altogether the 

 idea of the aggregation of the corpuscles being due to an attractive force 

 or energy, and refers it to adhesiveness or stickiness of the corpuscles ; in 

 his own words, " they merely stick together when brought into contact by 

 accidental causes." At the same time he states that this adhesiveness is 

 liable to great variations, both in the way of increase and diminution, by 

 very slight changes in the chemical qualities of the plasma. 



Dipping deeper into the writings of Lister, we find that this idea of 

 adhesiveness or stickiness of the corpuscles is retained in his explanation of 

 the nature of inflammatory stasis. And his views upon the subject generally 

 may be summed up in three propositions :— 



1 . The blood-corpuscles exhibit no tendency to unite together in healthy 

 blood within the vessels, although such blood may be in a state of rest. 



2. The corpuscles become suddenly adhesive (in 10 seconds) when, by 

 being shed, the blood is brought into contact with ordinary matter. 



