64 PROFESSOR CARUS ON DISSECTION. 



contributes to the food of plants. It is rendered soluble by a very 

 minute portion of any alkali, such as the ammonia disengaged from 

 dung, or by the potass, or the lime, which is often added to turf, or 

 other substances little soluble, or, as the farmers say, cold. The 

 substances thus dissolved are taken up by the roots as food. The 

 remarkable analogy, as to composition, between humine, and other 

 nutritive substances, such as gum, fecula, &c., explains and confirms 

 its property of contributing to the food of plants. 



[It must appear from the preceding details, that chemists and phy- 

 siologists need not now be at any loss to account for the existence of 

 the earths and the alkalies in the substance of plants. EDITOR]. 



ON DISSECTING AND PREPARING ANIMALS FOR 

 COLLECTIONS. 



BY PROFESSOR CARUS, OF DRESDEN *. 



THOUGH the art of anatomising the bodies of animals is essentially 

 the same as that practised upon the body of man, and though want of 

 space precludes me from treating the subject minutely, I conceive that 

 a few remarks may not be altogether unacceptable to those who feel 

 desirous of pursuing such studies for themselves. 



The first thing that I have to observe is, that all dissections of small 

 and soft objects, such as worms, zoophytes, insects, mollusca, and 

 embryos, where it is desirable to obtain even tolerably accurate results, 

 should be performed under water, by which the parts are kept floating 

 and separated from each other, and consequently present themselves 

 more distinctly. 



A very simple contrivance for investigations of this kind may be 

 prepared in the following manner : A mass of tough wax (not too soft) 

 is to be laid upon one, or more, porcelain saucers or capsules of diffe- 

 rent sizes, which are then to be put in a warm place until the wax 

 melts so as to cover the surface evenly to the depth of a half or a third 

 of an inch. If the object to be examined be laid upon this surface, it 

 may be fixed by needles in any position that is wished, and, when 

 covered with clear water, developed and dissected by means of suitable 

 instruments. Of them the best are very delicate forceps ; pointed, well- 

 made, sharp-cutting scissors ; and small knives like cataract-needles, 

 some round, others with cutting edges, and fixed in slender wooden 

 handles.* For separating parts I have also employed small horn probes 



* Translated from the German by R. T. Gore, Esq. Surgeon, Bath. 

 . f These instruments may be had of Mr. Blackwell, Surgeons' Instrument Maker, 

 Bedford Court, Covent Garden. 



