185 



CHAPTEK V. 



PREPARATION, MOUNTING, AND COLLECTION OP OBJECTS. 



Under this head it is intended to give such general directions 

 respecting the preparation, mounting, and collection of Objects, as 

 will supersede the necessity of frequent repetition when each par- 

 ticular class is described ; and also to enumerate the materials and 

 appliances which will be required or found advantageous. 



Section 1. Preparation of Objects. 



134. Microscopic Dissection. — The separation of the different 

 parts of an Animal or Vegetable structure by dissection, so as to 

 prepare any portion for being minutely examined under the 

 Microscope, should be accomplished, so far as may be found prac- 

 ticable, with the naked eye ; but the best mode of doing this will 

 depend in great degree upon the size and character of the object. 

 Generally speaking, it will be found advantageous to carry on the 

 dissection under Water, with which Alcohol should be mingled 

 where the substance has been long immersed in spirit. The size 

 and depth of the vessel should be proportioned to the dimensions 

 of the object to be dissected ; since, for the ready access of the 

 hands and dissecting-instruments, it is convenient that the object 

 should neither be far from its walls, nor lie under any great depth 

 of water. Where there is no occasion that the bottom of the 

 vessel should be transparent, no kind of Dissecting Trough is more 

 convenient than that which every one may readily make for him- 

 self, of any dimensions he may desire, by taking a piece of sheet 

 Gutta-Percha of adequate size and stoutness, warming it sufficiently 

 to render it flexible, and then turning-up its four sides, drawing- 

 out each corner into a sort of spout, which serves to pour away its 

 contents when it needs emptying. The dark colour of this sub- 

 stance enables it to furnish a back-ground, which assists the 

 observer in distinguishing delicate membranes, fibres, &c, espe- 

 cially when magnifying lenses are employed ; and it is hard 

 enough, without being too hard, to allow of pins being fixed into 

 it, both for securing the object and for keeping apart such por- 

 tions as it is useful to put on the stretch. When glass or earthen- 



