GENERAL REMARKS. 273 



named algae in it we get nothing but a swollen tube con- 

 taining swollen endochrome. Thus it is that many objects 

 are spoiled by the lack of knowledge of various preparers, 

 and also by the fact that some who should possess this 

 knowledge perform their operations so rapidly that it is 

 impossible they can produce uniform and permanent work. 

 And what do we see when we cast our eyes over the con- 

 tents of various cabinets ? Drawer after drawer is scanned, 

 and if the third of their contents are passable, from a 

 scientific point of mew y the possessor may be congratulated. 

 What can be done to get microscopy out of this groove ? 

 Slower work, more time in preparing, more care, the rejec- 

 tion of all middling or bad slides, the study of the object 

 before proceeding to mount it, mounting but few slides, and 

 last and not least, the careful study of the effects of the 

 various varnishes, cements, and reagents upon each other, 

 and upon the various objects they are intended to preserve. 



For the preparation and preservation of objects for the 

 microscope certain pieces of apparatus are either necessary 

 or useful, and although many makeshifts can be employed, 

 we give illustrations of the various instruments most gene- 

 rally used. 



Objects are generally mounted upon glass slides, or 

 " slips," as they are sometimes called, which measure three 

 inches in length by one in breadth, and of various thick- 

 nesses. They are sold either with rough edges or ground 

 edges as may be required, but there is so little difference in 

 price between the two varieties the latter possessing so 

 many advantages that the student is strongly advised to 

 purchase ground edges only. 



The ordinary flatted crown slips are the cheapest, but 

 should never be used for fine work, those of plate glass 

 being preferable, and even this should be selected if required 

 for mounting objects requiring delicate attention to illumi- 



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