212 LECTURE IX. 



less corpuscles of the blood as they usually appear and 

 are to be observed in people in the best state of health, 

 resemble pus-corpuscles in every respect (p. 180), one 

 essential point in the question is thus at the very outset 

 got rid of. In order, however, to render the subject to 

 some extent perspicuous, it is necessary to enter into the 

 consideration of the different points of view which are 

 here involved a little more in detail. 



Colourless blood-cells are so like pus-corpuscles as easily 

 to be mistaken for them, so that if in any specimen we 

 meet with such elements, we can never say with certainty 

 off-hand whether we have to deal with colourless blood-, 

 or pus-corpuscles. Formerly, and to some extent even 

 up to our own times, the view was very generally enter- 

 tained that the constituents of pus pre-existed in the 

 blood ; that pus was only a kind of secretion from the 

 blood, in somewhat the same way that urine is ; and that 

 it could also like a simple fluid return into the blood. 

 This view explains, you see, the conception which has 

 been so long preserved in the doctrine of the so called 

 physiological reabsorption of pus. 



It was imagined that the pus might be again taken up 

 into the blood from the different points at which it had 

 been deposited, and that a favourable turn was thereby 

 effected in the disease, inasmuch as the reabsorbed pus 

 was thus at last removed from the body. The tale went 

 that' in the case of a patient with pus in the cavity of the 

 pleura the disease might terminate in the evacuation of 

 purulent urine or purulent faeces, without the pus having 

 previously made its way directly from the pleura into the 

 urinary passages or the intestinal canal. It is therefore 

 admitted to be possible that pus may be reabsorbed and 

 conveyed away in substance. Afterwards, when the doc- 

 trine of pyaemia had more and more gained ground, these 

 cases were distinguished by the name of physiological re- 



