184 ON THE NATUKE AND PRINCIPLES OF 



that the capillaries have no proper coats, being mere 

 channels or grooves in a contractile parenchyma, I 

 cannot very clearly understand how the process of 

 effusion is to be accomplished. In a subsequent 

 pas~:ige of his paper (p. 141), Mr. Earle, in support 

 of his very mechanical doctrine as to the formation 

 of pus, endeavours to show that the several parts of 

 the blood exude in the order of their fluidity ; " the 

 finest and most fluid first, and the coarsest last." 

 But he certainly carries the idea too far when he 

 represents the red globules as passing in their turn 

 through the minute pores of the parenchyma, and 

 becoming there converted into pus-globules by the 

 mechanical detention of their colouring matter in 

 the meshes of the sieve through which they have to 

 pass. 



It is scarcely necessary to add that the present 

 inquiry embraces only the first stage of inflamma- 

 tion, in which the blood detained in the obstructed 

 vessels retains more or less fluidity, and is conse- 

 quently subjected to hydro-dynamic laws. With 

 the coagulation of the blood in its vessels the process 

 of effusion ceases ; and the changes which the effused 

 mutters and the solidified blood subsequently undergo 

 form a branch of pathological inquiry totally dis- 

 tinct from that which I proposed to undertake on 

 the present occasion. But even from the little 

 attention which it has been in my power to give to 

 this subject, I feel convinced that an investigation 

 of the pathology of the secondary effects of inflam- 

 mation, conducted on the principles previously indi- 

 cated, could not fail to afford most important and 



