182 LECTURE VII. 



semblance between the colourless cells of the blood and 

 pus-corpuscles still continues to occupy the attention of 

 observers, and it will probably still require a number of 

 years before the views entertained with regard to the 

 connection between the colourless corpuscles and pyaemia 

 have been rendered so clear that relapses on one side 

 or the other will not now and then recur. There is 

 namely this source of error, that upon examining a num- 

 ber of persons, in the blood of several among them cor- 

 puscles will be found which have only a single nucleus, 

 and that a very large one and not unfrequently provided 

 with a nucleolus, whilst in the blood of others no corpus- 

 cles will be seen which do not contain several nuclei. 

 Now, since these latter bear a great resemblance to pus- 

 corpuscles, those observers, who had previously chanced 

 to meet with nothing but uni-nuclear corpuscles in nor- 

 mal blood, cannot be blamed for believing, in another 

 case in which they see multi-nuclear ones, that they have 

 something essentially different before them, namely, pus- 

 corpuscles in the blood, and that the case is one of pyae- 

 mia. But, strange to say, the corpuscles with one nu- 

 cleus form the exception, and you may look for a long 

 time without finding blood in which all the cells have 

 only one nucleus. Oddly enough to-day, while occu- 

 pied in preparing the microscopical objects, I stumbled 

 upon a specimen of blood, in which scarcely 

 anything but cells with one nucleus are to be 

 met with, and these in extremely large num- 

 ^ ber ; it was taken from a man who died of 

 smallpox, and in whom a very highly remark- 

 able acute hyperplasia of the bronchial glands existed. 

 Now, one might be inclined to believe that these are 



Fig. 57. Colourless blood-corpuscles in variolous leucocytosis. a. Free or naked 

 nuclei, b, b. Colourless cells with small, simple nuclei, c. Larger, colourless cells, 

 with large nuclei and nucleoli. 300 diameters. 



