162 SUMMARY OF CURRENT RESEARCHES RELATING TO 



The dissecting clisl), as its name implies, is useful for animals of email 

 size only, such as earthworms, snails, frogs, &c. Although an ordinary 

 pic-dish can be, and has largely been, used for this purpose, it is 

 unquestionably a very imperfect article. Let us take, for example, a 

 frog : to learn its anatomy thoroughly, several days of work should 

 be spent upon its dissection. The dish should be filled to the depth 



Fig. 35. 



c, cover ; d, body of dish ; p, bed of paraffin. 



of about 1^ in. with a suitable mixture of paraffin wax and hog's lard, 

 melted together at a low temperature, and poured, whilst still fluid, but 

 on the verge of becoming solid, into the dish ; this will prevent any 

 marked after shrinkage. The animal should next be fastened upon the 

 paraffin when solid, with pins, and covered, or partially covered, with 

 dilute spirit. After a day or two, when some critical portion is about 

 to be examined, the student often finds, to his chagrin, that the liquid 

 around his dissection has insinuated itself between the sides of the dish 

 and the edges of the paraffin bed, by an almost imperceptible shrinkage 

 of the latter, sufficient, however, to render it so unsteady as to preclude 

 the possibility of work except with the utmost difficulty. To obviate 

 any such mishaps, the (anonymous) author has devised a dish, shown 

 in section at fig. 35. It may be oval or oblong (preferably the latter) in 

 shape ; its sides slope upwards and inwards, and thus effectually prevent 

 the bed of paraffin from shifting or floating during the dissection. The 

 upper rim of the dish should be indented, so as to admit of a cover 

 which will not easily slip off. Both dish and cover may be made of 

 earthenware, of indurated wood, or the new paper bottle material invented 

 by Mr. H. L. Thomas. 



Artificial Serum for Computation of Blood-corpuscles.*— M. Mayet 

 finds that the disadvantages of deformation, &c, which attend the use of 

 all the liquids employed in the computation of the number of blood- 

 corpuscles, may be avoided by using an artificial serum of the following 

 composition : — distilled water, 100 gr. ; jmre anhydrous neutral phos- 

 phate of sodium 2 gr. ; and cane-sugar to raise the density to 1085. 

 The form of the elements is preserved ; the density, slight viscosity, and 

 the presence of a neutral alkaline salt secure uniform distribution of the 

 elements ; the differences of level avoided in a less dense medium are of 

 little importance ; by altering the focus the leucocytes appear quite 

 distinct as brilliant bodies. 



* Comptes Eeiulus, cv. (1887) pp. 943-4. 



