DR. R. BAZIN 



203 



In drawing one makes use of squared paper, and the microscopic 

 image is reproduced in the way that the painter copies his picture. 

 To facilitate taking measurements, one of the squares in the centre 

 (see Fig. 2) is subdivided into four smaller squares, and one of the 

 small squares is again subdivided in the same way, with the aid of 

 a micrometer objective. Thus measurements can easily be made. 



When particles are to be counted, the diluted blood or bacteria- 

 preparation is placed in some cell which need not be squared; the 

 thickness of the cell must be known. It will be possible to count 

 the number of globules approximately, provided that one can get 

 them displayed in a single layer. The volume of the little drop 

 adhering to the pipette being knowm, the area which the drop occu- 

 pies can be measured with the aid of the graticule ; by counting the 

 mean number of red corpuscles per square, an approximate estimate- 



