92 JOURNAL OF THE [July, 



Cell-Theory." This address was illustrated by microscopical 

 preparations as stated below. 



OBJECTS EXHIBITED. 



1. Cornea of Cat, with basis substance stained with chloride 

 of gold showing reticulum. 



2. Cornea of Cat, stained with nitrate of silver. 



3. Section of human tooth with silver amalgam, showing re- 

 ticulum in the dentine. 



4. Dentine of human tooth, showing effect of amalgam. 

 All by Dr. Carl Heitzmann, 



Meeting of April 15TH, 1S92, 



The President, Mr. J. D. Hyatt, in the chair. 

 Fifteen persons present. 



OBJECTS EXHIBITED. 



1. Aventurine Feldspar (Sunstone), from Sussex Co., N. J. : 

 by James Walker. 



2. Section of the same by polarized light : by James Walker. 



3. Megalotrocha. — Rotifer colony — illustrating a convenient 

 method of transportation and exhibition : by James Walker. 



Mr. Walker explained the ingenious and convenient method of 

 handling the colony of Rotifers exhibited by him. A micro- 

 scopical cover glass is attached to one end of a thread by means 

 of a minute piece of wax. The cover glass is suspended in the 

 water of an aquarium. The thread passes over the edge of the 

 aquarium, and at the end, hanging outside, a balancing weight, 

 consisting of a small shot or any other convenient minute object, 

 retains the cover glass in any desired position in the water. 

 When a colony has attached itself to the cover glass, glass and 

 colony can be transported by transferring them uninjured to a 

 bottle of water, and they can be conveniently retained in any 

 position for examination on the stage of the microscope by trans- 

 ferring them from the bottle to a stage tank. 



Mr. Walker also described the piece of apparatus, constructed 

 by himself, for revolving the polarizing prism on the microscope. 

 A small shaft is attached to the substage, carrying at one end a 



