T. J. ENGLISH ON A PNEUMATIC INJECTING APPARATUS. 99 



hoped, comparable in accuracy with that of throwing the image of 

 the scale upon a screen, and is far easier of performance. 



Our best thanks are due to Mr. Curties, who has taken much 

 trouble, and made some valuable suggestions, in constructing the 

 instrument. If it prove useful to the members of the Quekett 

 Club, it will amply fulfil its purpose. 



Pneumatic Injecting Apparatus for Microscopical Purposes. 



By T. Johnston English, St. George's Hospital. 



{Bead October 26th, 1872.) 



The process of injecting for microscopical purposes is an opera- 

 tion which requires much skill and practice, and in order to obtain 

 really good results, much time and patience must be expended on 

 it. It is with a view to lessening its difficulties that I wish to bring 

 under your notice, to-night, this simple apparatus, the description 

 of which I will at once enter upon. 



The instrument consists of a Woulfe's bottle, having three necks 

 (pi. v. fig. ii, Nos. 1, 2, 3). No. 1 neck is fitted with a cork, through 

 which passes a piece of bent glass tube, of the diameter of a goose- 

 quill, one end of which reaches to the bottom of the bottle, and to 

 the other is tied about 12 inches of india-rubber piping of the same 

 diameter ; the glass tube is made perfectly air tight in the neck of 

 the bottle by sealing wax varnish, and the india-rubber one is 

 closed by apinch-cock. 



In No. 2 neck is a contrivance which answers the purpose of a 

 condensing syringe ; it is made of a piece of glass tubing 5in. or 

 6in. in length (fig. ii. A), passing through a cork, and also ren- 

 dered air tight by varnish ; to the uj)perendis tied an india-rubber 

 ball (B), having a small hole on one side (C) ; the lower qnd is 

 closed by a valve (D), opening downwards. This valve is made in 

 the following way : — A piece of gutta-percha is placed in boiling 

 water, and when perfectly soft and pliable, it is forced into the end 

 of the glass tube (see fig. iii.), so as to form a plug (E), extending 

 upwards for about ^in. It is then allowed to cool, and when hard, 

 it is trimmed with a pen knife. A small hole is then bored through 



h 2 



