ZOOLOGY AND BOTANY, MICKOSCOPYj ETC. 913 



can be mounted in toto, or sectioned. As the blastoderm is quite thin 

 during tlie cleavage stages, a whole series of these stages may be 

 mounted and studied from the surface to advantage. After removal 

 from the acid the preparations may be stained at once, and then 

 treated with alcohol and mounted in balsam. 



"Water-bath and Moulds for Imbedding.* — A, Andres, W. Gies- 

 brecht, and P. Mayer describe some minor arrangements which they 

 have devised for facilitating imbedding in parafi&n. 



First a water-bath, the principal advantage of which is that the 

 steam cannot reach the object, and that with a very small consumption 

 of gas or alcohol a constant temperature can be kept up during half 

 the day.| It is made of brass, contains a deep cylindrical and two 

 shallow depressions with cups of brass and several deep holes, in 

 which the glass tubes containing objects in chloroform and paraffin 

 can be put, as well as a thermometer. J Difficult objects are placed 

 with their tubes, from which the corks are previously removed, in the 

 water-bath whilst cold, and then gradually warmed ; afterwards they 

 are put in shallow saucers, a low temperature being kept up as long as 

 chloroform evaporates ; a deeper vessel contains the paraffin for im- 

 bedding. On one side is a slit for the insertion of slides to be 

 warmed. 



The imbedding is not done in boxes of paper or of tinfoil as 

 recommended by Kossmann, but in moulds with glass bottoms and 

 movable metal sides, so that they can be altered in size at will. At 

 the Zoological Institute at Leipzig they are made of type-metal. 

 The authors have altered them a little, giving them the shape 



of — I ~l — , and making them of brass in order to use as little 



metal as possible, and so obtain a uniform cooling of the whole mass. 

 The metal walls and glass bottom were rubbed each time with 

 glycerine, before being used, to prevent the paraffin adhering. For 

 exactly placing very small objects the boxes are coated with thin 

 collodion (after rubbing with glycerine), and then put into a water- 

 bath for the evaporation of the ether-alcohol, and a box is thus 

 obtained in which paraffin can be kept liquid for hours without 

 running out between the metal and the glass. The imbedding then 

 takes place quietly. The box is put in a small water-bath under the 

 dissecting Microscope, and after the objects are placed in position it 

 is quickly cooled by the emptying of the bath. 



Fearnley's Modification of the Groves-Williams Ether Freezing 

 Microtome. — Dr. Fearnley has devised the modification of the Groves- 

 Williams Ether Freezing Microtome § shown in fig. 170. The 



* MT. Zool. Stat. Neapel, iv. (1883) pp. 435-6. 



t E. Kossmann, Zool. Anzeig., vi. (1883) pp. 19-21, recommends for the same 

 purpose an air-bath which can be kept at 50° with a Kemp-Bunsen gas regu- 

 lator. 



X This water-bath has already been described in an original and similar form 

 by 0. O. Whitman. Amer. Natural., xvi. (1882) pp. 697-785. 



§ See this Journal, ii. (1882) p. 758. 



