194 LECTURE VIII. 



pneumonia or pleurisy the more readily the greater the 

 wateriness of the liquor sanguinis, and the poorer the blood 

 is in solid constituents, but it is an essential requisite that 

 the tibrine should coagulate slowly. If the duration of 

 the process be noted watch in hand, the conviction will 

 soon be acquired that a very much longer time passes 

 than is requisite for ordinary coagulation. From this 

 frequent phenomenon, as it is met with in the ordinary 

 formation of a crust upon the surface of inflamed blood, 

 gradual transitions are observed to a greatly increased 

 prolongation of the period during which fluidity is re- 

 tained. 



The most extreme instance of this kind as yet known 

 occurred in a case observed by Polli. In a vigorous man, 

 suffering from pneumonia, who came under treatment in 

 the summer, at a time which does not offer the external 

 conditions most favourable to slowness of coagulation, the 

 blood, which flowed from the opened vein, took a week 

 before it began to coagulate, and not until the end of a 

 fortnight was the coagulation complete. In this case, 

 too, occurred the other phenomenon which I had ob- 

 served in the pleuritic exudations, namely, that decom- 

 position (putrefaction) took place in the blood at an 

 unusally late period in proportion to this lateness of 

 coagulation. 



Now since phenomena of this kind are observed to 

 occur with especial frequency in chest affections, a fre- 

 quency so especial indeed that the buffy coat was long 

 since designated Crusta pleuritica, there would seem to 

 be some grounds for inferring from this, that the function 

 of respiration has a definite influence upon the occur- 

 rence or non-occurrence of the fibrinogenous substance 

 in the blood. At all events, the peculiarity possessed by 

 the lymph is under certain circumstances transmitted to 

 the blood, so that either the whole of the blood partakes 



