THE MICROSCOPE. 117 



When I reflect on the immunity of hard-working people from 

 the effect of wrong and over-feeding," says Dr. Boerhaave, "I can- 

 not help thinking that most of our fashionable diseases might be 

 cured mechanically instead, of chemically, by climbing a bitterwood 

 tree, or chopping it down, if you like, rather than swallowing a de- 

 coction of its disgusting leaves." — Ex. 



Copal Varnish. — Pale copal varnish, of the consistency of oil, 

 is recommended as a substitute for Canada balsam. Mr. Derby 

 writes in the Journal of the Queckett Microscopical Club, that he 

 finds it much pleasanter to use than Canada balsam; it makes no 

 bubbles, which sorely try beginners working with balsam; it has 

 nearly the same refractive index as balsam. He has mounted speci- 

 mens in copal, dispensing with the cover glass altogether. The 

 varnish dried rapidly if slightly heated, and is hard enough to stand 

 wiping and rubbing with a soft brush. — Medical Herald. 



Coloring Living Cells.— M. A. Certes details in the Comptes 

 J^e?idus a series of interesting experiments, which seem to demon- 

 strate the possibility of staining living cells. He uses a weak solu- 

 tion of cyanin in serum (which is a better solvent than water). Infu- 

 soria are stained a pale blue, and live for 36 hours. White blood- 

 corpuscles of the frog, stained with cyanin and kept for 24 hours in 

 a moist chamber, still exhibit amoeboid movements. Cyanin tinges 

 the fat granules of the protoplasm, it has no effect on the nucleolus, 

 cuticle, vacuoles or cilia. — Medical Herald. 



Origin of Yf.llow Fever. — Dr. Manuel Da Gama Lobo of Rio 

 Janeiro, physician to His Majesty, the Emperor of Brazil, has been 

 prosecuting some microscopic investigations relative to the land 

 origin of yellow fever. He has found at Vera Cruz, Mexico, and 

 Havana, Cuba, sufficient evidence to warrant him in stating that 

 these localities are fruitful sources of a poison which causes the dis- 

 ease. The toxic agent is derived from a species of infusoria, the 

 opunsia Mexicana, which belongs the family of hacillariun. — Ex. 



Curiosities of Adulteration. — A school-master sends the fol- 

 lowing singular statement to the London Lancet : "I am at the head of 

 a town school, and a short time back gave Breadmaking to a class 



