438 THE AMERICAN MONTHLY [Dec. 



rum of animals inoculated with cancerous elements seemed 

 to cure cancer by fibrous transformation. Its action was 

 much more certain he said, when it was employed in the 

 beg-inning- of the disease. He thoug-ht its employment pre- 

 sented no dang-ers, except in cases of extensive lesions. — 

 N. Y. Med. Jour. 



MICROSCOPICAL SOCIETIES. 



Calcutta Microscopical Society. 



At the April meeting- Mr. W. J. Simmons described bis 

 method of making- an observation of dust with a view of 

 detecting- in it air-borne spores which are said to cause 

 molds to g-row in a manner which the earlier observers be- 

 lieved favored the doctrine of spontaneous g-eneration. 

 The method is simplicity itself, and consists in placing- a 

 drop of pure g-lycerine on the center of a slip of g-lass 

 measuring- three inches by one inch. The drop is smeared 

 over the g-lass lig-htly so as to cover a surface of about 

 three-quarters of an inch in diameter, and is then exposed 

 to the air for two or three days. When the dust which 

 settles on the smear is to be examined under the micro- 

 scope, a circular cover g-lass is placed on it, and the deposit 

 is now shown by the microscope to be composed of a most 

 heterogeneous collection of objects. Fibers of all sorts, 

 the scales from insects, wing-s, root, pollen, starch, down, 

 frag-ments of epidermis, and of the cuticle of plants, hair, 

 entire mites, numberless inorg-anic particles, charred 

 straw, portions of insects, hairs from plants, and several 

 spores of fung-i are thus revealed. 



If a drop of g-lycerine, half an inch in diameter, arrests 

 so many spores, how many do we inhale daily, and how 

 many are deposited on our food in the course of a day? 

 The study of dust is not one suited to a beg-inner in mic- 

 roscopy, because it presupposes familiarity with the thous- 

 and and one objects which are certain to be present on the 

 g-lass slip; but it presents no insuperable difficulties, and 

 does not demand any special or costly appliances. 



