A NEW GROWING-SLIDE. 119 



of the Editor from the current volume of the Royal Microscopical 

 Society's Journal, page 19 : — 



" It consists of the usual glass slip, A A (3 in. by i in.), 

 having a narrow ledge of glass, B, about ^th of an inch wide, 

 and extending nearly its whole length, fastened to its lower border 

 with marine glue ; to this is cemented at right angles a strip of 

 thin covering-glass, C, about ^ of an inch wide, and at about 

 I ^th inch from the end of the slide, having a narrow channel 

 cut through it for the passage of an intake thread, D. A 

 similar strip, E, having a similar cut through it for the passage of 

 an outlet thread, F, is cemented at the same distance from the 

 opposite end of the slide. In order that organisms near the 

 bottom of the cell may be benefitted by a constant change of 

 water, a very narrow slip, H, of the same thin covering-glass is 

 cemented to the inner side of the outlet end of the cell, com- 

 mencing at the top of the slide and extending very nearly to the 

 bottom, so as to leave only about Vieth inch between E and H. If 

 the intake-thread is now connected with a bottle of water placed 

 above the level of the slide, water entering by it will pass in a 

 diagonal direction from D to the left and bottom of the cell, where 

 the suction set up by the siphon-like action of the outlet thread 

 makes itself felt, and there is a regular current in the direction of 

 the arrows. 



The front of the cell is formed of a piece of thin cover-glass of 

 I J inch by ^ ; and two small square blocks of glass, I, cemented 

 on each side, will hold this cover-glass sufficiently firm to prevent 

 it sliding on the organism and crushing it. 



Such a Growing-Slide will hold about one drachm of water, 

 and taking the rate of the drops from the outlet-thread as about 

 one per minute, the whole of the water will be changed once 

 every hour; while at the same time the current is not strong 

 enough to carry away any but the finest and lightest particles. It 

 allows of fair observation with a J-inch objective." 



Another very simple plan was suggested at the same meeting, 

 which consisted in making a small cell of the ordinary thin 

 covering-glass, and then surrounding it with blotting-paper, which 

 must be kept constantly wet ; by this means, large monads might 

 be kept under continual observation for three or four weeks. 



