PRACTICAL MICROSCOPY. 



not say that all preparations which I call trivial are useless ; 

 most certainly not. If they are not satisfactory to savants 

 they interest amateurs, and they teach many things that 

 otherwise would not have been known. They are also 

 useful in England, where they are sold in large numbers, 

 because among our neighbours the microscope is more used 

 for amusement and as an object of luxury than for working 

 purposes." 



We cannot fully endorse the opinions of Dr. Pelletan, 

 though it would be more satisfactory to find an improve- 

 ment in the general mounting of objects ; and to prepare 

 one or two slides of a subject well would be of far more 

 value than mounting a host of second-rate ones for ex- 

 changes ; and further, we would like to see far more experi- 

 ments upon subjects mounted in different media than exists 

 at present, and what with interchange of opinions upon this 

 subject at our various microscopical society meetings, we 

 could scarcely fail in rendering our cabinets more inter- 

 esting and our preparations more permanent. 



The mounting of objects and their preparation for this 

 purpose is by no means an easy operation, especially if our 

 slides are to be permanent and of scientific interest. The 

 conditions are ever varying, and it requires a good know- 

 ledge of the properties of the various substances generally 

 used in this branch in order to know beforehand what their 

 actions will be on this or that objector portion of it. Even 

 a process which would do well for some particular class of 

 objects is often found to fail with some of them. If, for 

 instance, the marine alga Bangia fusco-purpurea be mounted 

 in balsam and benzol it will represent it in its natural con- 

 dition, while if we try to preserve Dasya coccinea in the 

 same manner we shall fail miserably. In other instances 

 we may find many algae which may be successfully mounted 

 in Deane's medium, while if we try to put up the first- 



