PROFESSOR CARUS ON DISSECTION. 



65 



and fine brushes; whilst for examining them, a good magnifying glass 

 is frequently indispensable. If it is wished to preserve a preparation 

 thus made, wax, coloured at pleasure as for the purpose of injections, 

 is to be formed into little tablets about one-fourth of an inch thick : one 

 of these is then to be placed upon the saucer or capsule containing the 

 preparation ; the latter may then be transferred to it, arranged suitably 

 upon it, fixed there by means of short needles, and both together then 

 placed in alcohol. Ncr must I forget to mention, that the examination 

 of very delicate organizations may frequently be conducted with greater 

 facility and accuracy, if the object be previously- allowed to remain 

 some time in spirit, and thereby to become harder and contracted. 

 This applies particularly to the dissection of nervous organs, and to 

 the examination of very small embryos, of mollusca, and worms. 



There are various modes of destroying worms, insects, mollusca, &c, 

 for the purpose of dissecting, without injuring their organization : mol- 

 lusca, snails, for instance, as Swammerdam has remarked, are to be 

 allowed to die in water, because by that means their body swells, and all 

 the parts become more distinctly visible ; they may be afterwards kept in 

 spirit (though not too long) for dissection. Worms, the larger zoophy- 

 tes, (for the smaller must be examined while alive,) caterpillars, &c, 

 and also the smaller amphibia, and fishes, are best destroyed by means 

 of spirit. Insects, on the contrary, by being dipped rapidly in boiling 

 water, or in oil of turpentine. 



As regards the dissection of larger animals, we may here use with 

 advantage knives of a large size ; and, instead of forceps, suitable hooks 

 with handles. 



In animals of considerable size we can generally make artificial ske- 

 letons only after the bones have been sufficiently cleaned by boiling or 

 maceration. In smaller animals, on the contrary, such as birds, am- 

 phibia, and fishes, of which last it is very difficult to make good skele- 

 tons, the object will be best accomplished by at once making.the bones 

 as clean as possible, without injuring the capsular ligaments, soaking the 

 preparation in water, that is incessantly changed; and lastly, bleaching 

 it for some time in the sun. Lastly, we may mention injections as 

 affording a very essential assistance in zootomical investigations for 

 physiological purposes : in small animals, and in the more minute parts, 

 these must consist of compositions with wax, very fluid and coloured ; 

 best of all of mercury. The latter, however, is not suitable for very soft 

 bodies, such as medusee, &c, in which cases we may employ injections 

 of coloured milk, and similar substances. 



VOL. T. NO. II. (FEB. 1833.) F 



