1 82 PREPARATION AND MOUNTING 



the force required grows greater, yet care must be taken not 

 to use too much, or the vessels will burst, and render all the 

 labour fruitless. The movement of the piston must be 

 occasionally so slow as to be almost imperceptible, and for 

 this reason the piston-rod is sometimes marked with lines 

 about one- eighth of an inch apart. 



19. Of course, during the whole process the injecting 

 fluid and subject must be kept at a temperature high enough 

 to allow the liquid to flow freely ; and the escape of a little 

 of it need cause no fears to the operator, as it is almost im- 

 possible to fill a subject without some loss. When the 

 injected object has received sufficient fluid, it should have a 

 plump appearance, owing to all the vessels being well filled. 

 The vessel must then be tied up where the pipe was inserted, 

 and the whole left in cold water two or three hours, after 

 which time it may be mounted ; but it may be well to notice 

 a few things which the beginner ought to know before enter- 

 ing into that part of the process; and he may be here informed 

 that it is not necessary to mount the objects immediately,, 

 otherwise it would be impossible for one person to make 

 use of half of any large subject, as it would be in a state 

 of decay long before each part could have been examined 

 and separated. Large pieces should be therefore immersed 

 in equal parts of spirits of wine and water, or glycerine, 

 which some think better still, and thus preserved in bottles 

 until time can be given to a closer examination. 



20. In operating upon large subjects, entire animals, &c., 

 the constant pressure required by the piston of the syringe 

 grows wearisome, besides occupying both hands, which is 

 sometimes inconvenient when working without assistance. 

 To obviate this, flother way of driving the syringe was 

 published in the Micrographic Dictionary which I will 

 quote here: "We have therefore contrived a very simple 

 piece of apparatus, which any one can prepai'e for himself, 

 and which effects the object by mechanical means. It con- 

 sists of a rectangular piece of board, two feet long and ten 

 inches wide to one end of which is fastened an inclined 



