1899] MICROSCOPICAL JOURNAL. 207 



Notes on Microscopy. 



JOHN H. COOKE. 



Against Rust. --In biological laboratories, where the 

 microtome is in constant use, it is of im[)ortance that the 

 edges of the microtome knives should be kept in as per- 

 fect a condition as possible. To prevent dulling of the 

 edge, which results from oxidation, the knives should be 

 kept immersed in a one per cent solution of carbonate of 

 sodium. This treatment will not only prevent their rust- 

 ing, but will also render them perfectly asceptic. 



Yeasts. — Dr. Buchner's recent discovery that the al- 

 coholic fermentation set up by the yeast plant, is due to 

 the chemical power of an amyloyte acting in a manner 

 similar to digestive ferment, caused a sensation among 

 those who had hitherto held that the action of yeast 

 could not be dissociated from the living plant. To dem- 

 onstrate the action of this ferment, the yeast cells should 

 be thoroughly disrupted by grinding them up with quartz 

 sand, and, subsequently, be submitted to a pressure of 

 about five hundred atmospheres. Some few cells may 

 escape destruction in this process, and these should be 

 searched for with the microscope, and either disrupted or 

 removed. The resultant powdered mass will act similarly 

 to untreated yeast, thus showing that the fermentative 

 action hitherto attributed to the living cell is, in reality, 

 due to a fermentative enzyme. 



The nucleus of the malarial parasite has been demon- 

 strated by Ziemann with the aid of a new stain, consist- 

 ing of a mixture of a 1 per ct. watery solution of rectified 

 methylene-blue and a 1 per cent watery solution of eosin. 



Objective. — At a recent meeting of the Royal Micro- 

 scopical Society of London, Mr. E. M. Nelson exhibited 

 a new objective by Zeiss, called a "plankton-searcher," 

 a low-power water immersion objective, designed for use 

 in examining living objects in water. 



