1880.] 



MICROSCOPICAL JOURNAL. 



85 



best and most manageable medium 

 for imbedding that has yet been 

 suggested. We shall, therefore, 

 describe the method of using it in 

 some detail. 



When a certain quantity of hard 

 soap is dissolved in hot alcohol and 

 the solution allowed to cool, the 

 resulting mass will be hard or soft, 

 opaque or pellucid, according to 

 the strength of the alcohol or the 

 proportion of water which the soap 

 contained. If 5-6 parts of rather 

 dry soap are dissolved in 100 parts 

 of 96 per cent, alcohol, there will 

 be obtained a solution which, on 

 cooling, will yield a hard and trans- 

 parent mass, but the warmth of the 

 imger will cause it to liquify again. 

 A larger proportion of the soap 

 will furnish a white mass, but the 

 addition of a certain quantity of 

 water to the solution will cause it 

 to solidify clear and transparent. 

 An excessive portion of water will 

 cause the liquid to harden more 

 slowly or at a lower temperature. 

 The more soap there is in the al- 

 coholic solution, the more water is 

 required to produce a mass that 

 possesses the requisite degree of 

 hardness combined with transpar- 

 ency. The soap-mass possesses its 

 greatest possible consistence and 

 elasticity when the minimum quan- 

 tity of water required to clear it is 

 used. 



To prepare an imbedding mixture, 

 dissolve about 25 grammes of finely 

 shaved soda-soap in 100=- «=• of 96 

 per cent, alcohol, by heating on a 

 water-bath. To test the mixture, 

 pour a small quantity of the warm 

 solution into a watch glass, and 

 notice the result of cooling. The 

 opaque mass that will probably be 

 obtained, must be rendered trans- 

 parent by the addition of water 

 in small quantities, testing in the 

 same manner after each addition, 

 until a clear product is obtained. 



From 5-10<=- "=• of water will prob- 

 ably suffice. 



The consistence of the solidified 

 mass can be altered to suit different 

 objects, by using more or less soap 

 in proportion to the alcohol, thus 

 the author has used solutions con- 

 taining 10, 20, 30 and 40 per cent, 

 of soap. 



o 



Spring Collections. 



A collecting-bottle that is more 

 attractive in appearance, and smaller 

 than the one described in the March 

 number of the Journal, may be 

 made according to the same general 

 plan ; but for the jelly-glass a 3-oz. 

 wide-mouthed bottle should be sub- 

 stituted, and, instead of the common 

 funnels, use the glass tubes with 

 funnels blown on the ends that 

 chemists know as "funnel-tubes." 

 Cut off these tubes to a suitable 

 length, put them into the bottle 

 just as the funnels w^ere put in be- 

 fore, and the apparatus is complete. 



Perhaps there is nothing more 

 interesting to observe at this season 

 than the development of snails and 

 frogs from their spawn ; the speci- 

 mens for study are readily obtained. 



Frog-spawn can be found in any 

 frog-pond, either attached to various 

 articles, such as submerged plants, 

 twigs, etc., or floating near the bor- 

 der of the pond, where the wind 

 has blown it. It looks like a large 

 mass of jelly, filled with dark-col- 

 ored spots which are the embryos. 



The mass must be carefully 

 handled and placed in a large jar, 

 with sufficient water, when the en- 

 tire process of development, first 

 into tad-poles and then into frogs, 

 can be followed. After the tad- 

 poles are hatched, and show signs 

 of changing to frogs, they should 

 be provided with resting places at 

 the surface of the water. 



Snail-spawn can be obtained by 



