438 



CHAPTER VII 



PREPARATION, MOUNTING, AND COLLECTION OF OBJECTS 



UNDER this head it is intended to give an account of those materials, 

 instruments, and appliances of various kinds which have been found 

 most serviceable to microscopists engaged in general biological re- 

 search, and to describe the most approved methods of employing 

 them in the preparation and mounting of objects for the display of 

 the minute structures thus brought to our knowledge. Not only is 

 it of the greatest advantage that the discoveries made by microscopic 

 research should as far as possible be embodied (so to speak) in 

 * preparations,' which shall enable them to be studied by every one 

 who may desire to do so, but it is now universally admitted that 

 such ' preparations ' often show so much more than can be seen in 

 the fresh organism that no examination of it can be considered as 

 complete in which the methods most suitable to each particular 

 case have not been put in practice. It must be obvious that in a 

 comprehensive treatise like the present such a general treatment of 

 this subject is all that can be attempted, excepting in a few instances 

 of peculiar interest ; and as the histological student can find all 

 the guidance he needs in the numerous manuals now prepared for 

 his instruction, the Author will not feel it requisite to furnish him 

 with the special directions that are readily accessible to him else- 

 where. 



MATERIALS, INSTRUMENTS, AND APPLIANCES. 



Glass Slides. The kind of glass best suited for mounting objects 

 is that which is known as * patent plate,' and it is now almost in- 

 variably cut, by the common consent of microscopists in this country, 

 into slips measuring 3 in. by 1 in. For objects too large to be 

 mounted on these the size of 3 in. by 1^ in. may be adopted. Such 

 slips may be purchased, accurately cut to size, and ground at the 

 edges, for so little more than the cost of the glass that few persons 

 to whom time is an object would trouble themselves to prepare 

 them ; it being only when glass slides of some unusual dimensions 

 are required, or when it is desired to construct * built-up cells,' that 

 a facility in cutting glass with a glazier's diamond becomes useful. 

 The glass slides prepared for use should be free from veins, air-bubbles, 

 or other flaws, at least in the central part on which the object is 

 placed ; and any whose defects render them unsuitable for ordinary 

 purposes should be selected and laid aside for uses to which the 

 working microscopist will find no difficulty in putting them. As 



