1894.] MICROSCOPICAL JOURNAL 283 



upon the screen photographs of yeast cells, in conjunction with 

 a network of squares, the sides of which measured only 1-3750 

 of an inch. In the case of some other organisms, squares 

 measuring 1-7500 of an inch were employed. 



MICROSCOPICAL APPARATUS. 



A Convenient Sub-stage Condenser. — A periscopic eye 

 piece set in the sub-stage with an adapter will afford a very 

 good sub-stage condenser. 



Polarizers are usually fitted with an adapter which may be 

 removed and used with eye-piece in the sub-stage. The con- 

 denser certainly improves the performance of the microscope, 

 it renders the light more pleasant to the eye and better defines 

 the objects. Often, things hardly visible without the condenser, 

 for example, bacilli tuberculosis, become distinct when it is em- 

 ployed. With low powers the condenser should be moved 

 down away from the objective and with high powers brought 

 up close to them. No one who has ever used a condenser 

 would. be without one. The light is also much improved by 

 using a microscopic lamp with a blue glass inserted in the 

 bull's eye.— L. C. W. 



MICROSCOPICAL MANIPULATION. 



New Method of Staining Micro-Organisms in the 

 Blood. — A comunication on this subject was made by M. H. 

 Vincent at the last meeting of the Societe de Biologic. 



The process is applicable to every variety of micro-organism 

 occurring in the blood, but is particularly serviceable in micro- 

 scopical examinations in bacteria, which do not take coloration 

 by the method of Gram, and of various i)arasites, such as hema- 

 tozoa of paludism. 



The process is based on the following principle, viz., coloring 

 matters fix themselves not to the protoplasm, but to the hemo- 

 globen itself. If, therefore, the latter col or- taking constituent be 

 made artificially to disappear and the coloring agent be then 

 brought to bear, the blood globules which mask the bacteria be- 

 come invisible, and the microbes alone remain colored and 

 stand out upder the paicroscope with great clearn^pg. 



