I 



Boyal Microscopical Socieiy. 99 



of the blotting-paper, which, from the glass vessel to the left of the 

 stage,* is by capillarity always renewing its moisture. 



It will be seen that the instrument must be horizontal ; but 

 there is no inconvenience arising from this if it be placed on a 

 sufficiently low support ; and it will be found in practice that it 

 may be worked for a long time without any other change in the 

 arrangement than the screwing up or down of the fine adjustment. 

 The difficulties in working are few, and can be best discovered and 

 overcome in practice. 



Experiments on the Effect of different Temperatures on the 

 ^ Vitality and Development of the Monads described. 



Our method was to take a drop of the fluid containing the forms, 

 and put it upon an ordinary glass slip, and cover it with a tliin 

 cover. It was then examined with great care, and a record made of 

 what it contained and the condition the objects were in. It was then 

 placed in the brass box a, PI. LIV., upper portion, by taking off 

 the well-fitting cover h. Two pairs of ledges inside enabled us to 

 place a dozen or more slides within it. The cover had a suitable 

 thermometer d, fitted in at c with cork, the bulb reaching exactly 

 the middle of the inside of the box. Underneath this box a Bun- 

 sen's bm*ner e was placed, with a series of jets in the form of a 

 parallelogram, to correspond with the shape of the box. 



A series of slips, having been carefully examined and inserted, 

 and the cover of the box put on, heat was steadily and cautiously 

 employed until the mercury stood at the desired point. It was 

 then carefully maintained at this, in some cases ten and in others 

 fifteen minutes. The box was then allowed to cool slowly, and 

 when cold the objects were removed, and a drop of distilled water 

 inserted by capillarity. Each slide was then immediately examined 

 and reported upon. It was then inserted in a large moist chamber, 

 to be watched regularly through succeeding hours or days. The 

 moist chamber we devised is simple and effectual. It is drawn on 

 PI. LIIL, Fig. 6. a is a tray standing on two legs c, d, and 

 further supported by the trough h. This trough holds water. 

 A piece of bibulous paper is cut to the size of the tray, but with a 

 flap to go over the edge e and fall down uito the trough h. This is 

 the " bed " on which the shps are placed. Another piece of blot- 

 ting-paper is now cut to the same shape and size, and then is 

 further cut as shown in Fig, 7. c is the flap to go into the trough ; 

 d is the part that will lay on the " bed " ; but it has pieces cut out, 

 as at e,f, g\ and beside this, circular apertures, considerably larger 

 than the covermg glass on the slip, are cut out, as h, i, j, &c. This 



* The vessel will of course require refilling according to the rapidity of the 

 evaporation ; but we now purpose obviating this to a large extent by using a 

 vessel formed on the principle adopted in the construction of the water trough 

 of a modern aviary. 



