202 THE AMERICAN MONTHLY July] 



power for which the iiu-;tiuim'nt has hoon iiukU- ami the possi- 

 bilities by betweeii ')0 ami 'JoO diaineter lua^^niticatioii. To 

 tind the actual Held, measure the diameter of the field in mill- 

 meters and ilivide this by the previously ascortaineil majiniti- 

 uition. The diauieter of the actual tield will bo the exact dis- 

 tance between the Hues of the spiral groove. In most instru- 

 ments, 100 to 150 diameters give fields of 1 millimeter diameter, 

 just wide enough ft>r the grooves, while the powers beyond these 

 furnish too small a space. It should therefore be exactly fitted 

 for one of the lower ])owcrs on the nose-piece of the microscope. 

 C, the table, is firmly but not permanently attached to the stage 

 of the microscope by means of pins and sockets, clamps, or 

 screws according to the stage of the instrument. 



In summing up, therefore, it is claimed, that this instrument 

 brings every portion of the slide in succession and by the short- 

 est route into the focus of the microscope ; second, that it ad- 

 mits of more definite estimates of the contents of a slide ; and 

 third, that any object on the slide may be easily and definitely 

 recorded and found again with very little trouble. A patent 

 lias been applied for. 



Two New Blood Stains. 

 By W. DRESCHER, 



KOCIIESTKK, N. Y. 



Micro?coj»ists and Clinicians have for some time felt the need 

 of some method for the fixing and differential staining of the 

 various formed elements of the blood. Many attempts have been 

 made to answer this need, many methods have been suggested, 

 none seeming, however, to combine so many of the essential 

 qualities of a "good stain " as the method suggested and j)er- 

 fected by Dr. Ehrlich of Berlin. 



We should add to our list of re-agents two of the blood-coloring 

 solutions, now very generally used in Europe. In doing so, we 

 aid in bringing them into more general use, particularly in the 

 laboratories and hospitals of this country. 



The .stains are, — (TjEhrlich's Neutroi)hile Stain, (2jChenzin- 

 skie's Eosin Methylene Blue Solution. The formuhe for which 

 are as follows : 



