16 



THE AMERICAN MONTHLY 



[January, 



mains, however, that others have not 

 been successful in its use. Whether 

 the reason is that the glycerin used 

 by different persons possesses differ- 

 ent properties, or that there are differ- 

 ent methods of using it, or that the 

 specimens mounted are not always 

 properly prepared, it is impossible to 

 say. Certain it is that we have seen 

 so many failures with glycerin mount- 

 ing — not in the sealing of the cells, 

 which is a very simple matter, but in 

 the preservation of the tissues — that 

 we take occasion to caution micro- 

 scopists against the too general em- 

 ployment of this agent. 



The great value of glycerin in 

 mounting arises from its density and 

 perfectly neutral character. By its 

 use we are able to produce mixtures 

 of any desired specific gravity ; and 

 it seems that by mixing glycerin 

 and alcohol and water in proper pro- 

 portions — as has already been rec- 

 ommended in these columns — the 

 objectionable effects of strong glycerin 

 are avoided. The alcohol seems to 

 harden and preserve the specimens, 

 the glycerin gives density to the me- 

 dium, which prevents the injurious 

 effects of osmosis that would result 

 with alcohol, or alcohol and water. 

 While we can i-ecommend the use of 

 such a mixture, we would object most 

 decidedly to the employment of a 

 mixture of glycerin and water alone. 

 The hardening effect of the alcohol 

 must be regarded as essential to the 

 preservation of delicate tissues. 

 o 



Microscopical Societies. — In al- 

 most every society there are a certain 

 number of members who are con- 

 stantly endeavoring to make the meet- 

 ino-s more and more interesting and 

 useful. We have always had in mind 

 the interests of such members, and 

 whenever any suggestion has come 

 to us which seemed useful to them it 

 has found its way into the Journal. 

 The plan of giving practical demon- 

 strations at the meetings of societies, 

 illustrating methods of preparing and 

 mounting specimens, has always 



seemed a most excellent one. The 

 Quekett Microscopical Club of Lon- 

 don adopted this plan some time ago, 

 and it has proved so beneficial in its 

 results that at a recent meeting it was 

 determined to continue the demon- 

 strations during the ensuing year. On ^ 

 the "gossip nights," which are in- 

 formal gatherings to which members 

 bring their microscopes and objects, 

 it has been decided that there shall be 

 six demonstrations during the year, 

 beginning in December and ending 

 in May. Members are asked to men- 

 tion the subjects about which they 

 wish to be instructed, and the council 

 then makes a selection of subjects for 

 the different nights, which are an- 

 nounced, with the dates. This plan 

 has proved so satisfactory in London 

 that there is every reason to suppose 

 it would be equally beneficial here. 

 o 



Postal Microscopical Club. — 

 Early last year we stated our inten- 

 tion to publish notices of the boxes 

 of the Postal Microscopical Club as 

 the}^ came to our hands. It has been 

 clearly impossible for us to do so, but 

 this year, it is hoped, we will be able 

 to get into a new circuit and receive 

 the boxes regularly. We will then 

 fulfil the promises of the year that 

 is passed. 



Those who contribute slides should 

 understand that it is not intended to 

 make these notes severely critical. 

 Their purpose is quite different. They 

 are intended to be an aid to those of 

 our subscribers who receive the boxes, 

 by indicating, so far as possible, the 

 most interesting and instructive feat- 

 ures of the objects sent around, giving 

 such hints about their preparation and 

 mounting as may occur to us at the 

 time. 



Sense of Hearing in Insects. — 

 It has long been known, or at least 

 supposed, that some insects are sensi- 

 ble of sounds through the vibration of 

 certain hairs on different parts of the 

 body. It is difficult indeed to prove 

 such a supposition, but \eiy careful ex- 



