126 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



(2) Preparing Objects. 



Delepine Ether Freezing Box. — This is an auxiliary of the Dele- 

 pine microtome described on p. 128, and is also brought out by Messrs. 

 R. and J. Beck. Although it has been in use for over sixteen years, it 

 has not previously been described. The arrangement of the parts is so 

 designed that the specimen to be cut will remain frozen for a much 

 longer time after ceasing to work the bellows than is usually the case. 

 Scarcely any ether is wasted, as the unevaporated and recondensed ether 

 drops back into the reservoir, the only waste being that which passes 

 out with the air ; moreover, an object as large as 2 in. in diameter can be 

 successfully frozen, thus enabling such a specimen as a whole eye to 

 be cut into sections without any difficulty. The ether is introduced into 

 the main chamber by unscrewing the funnel cap D (fig. 30), and the 

 box B may be replenished, if required, during use. The bellows are 

 attached to the end of the tube L, which communicates directly with the 

 nozzle C ; the distance of C below the freezing plate A is adjustable, so 



Fig. 30. 



that'the'ether may be sprayed over a large or small surface, according 

 to the size of a section under the knife. After a few minutes' working 

 the whole of the ether in B will become almost as cold as the freezing- 

 plate ; and to utilise this cold as much as possible, a tube F fixed to the 

 freezing-plate passes down into the ether as in B, and thus equalises the 

 low temperature over the whole of the large plate A much more effi- 

 ciently than could be the case if only a single point were the source of 

 the cold. The freezing-plate A and the tube F are insulated effectually 

 from the rest of the metal-work by the solid vulcanite carrier G. The 

 various parts are detachable for convenience of cleaning. The air from 

 the bellows, after issuing from C, passes with its ether vapour through 

 holes in the top of the tube F, and thence out of the box by the tube E. 

 Any superfluous ether, as well as the water separated from the ether, 

 may be drawn off by means of the tap E. 



Microtechnique for the Study of Sponges.*— Dr. E. Rousseau com- 

 municates a summary of the procedures employed by him in the study 

 of sponges. The first two steps are the same for the three kinds, 

 Calcareous, Horny, and Siliceous :— (1) Thin little bits are removed 



* Ann. Soc. Beige Micr., xxiv. (1S99) pp. 49-56. 



