VON KOCH'S COPAL METHOD. 205 



xiv, 1880, pp. 313, 314; Journ. Roy. Mic. Soc. [N.S.], ii, 

 p. 278). 



It would probably be advantageous to add some preserva- 

 tive substance. 



308. ROBERTSON'S Grape-sugar Method (Journ. ofAnat. and Physiol., 

 xxiv, 1890, p. 230 ; Zeit.f. wiss. Mile., vii, 1, 1890, p. 33). 



Grape-sugar 5 parts. 



Dextrin . . . . . . 10 



Boric acid 1 part. 



Mix and add three drachms o water for each quarter of an ounce of the 

 mixture, and dissolve by heating to boiling-point. After cooling, add 6 

 drops of carbolic acid for each ounce of the solution. The directions for 

 using this mass are practically identical with those given by Joliet for his 

 gum and glycerin mass, last section. 



The mass above described is advised for fresh tissues. For hardened 

 tissues a mass is given containing two parts of soft soap (sapo mollis) instead 

 of the 1 part of boric acid ; the rest as before. 



309. Strieker's Gum Method (Hdb. d. GewebeL, p. xxiv). A concen- 

 trated solution of gum arabic. The object may be prepared in alcohol and 

 imbedded in the gum in a paper case. The whole is thrown into alcohol, and 

 after two or three days may be cut. 



I have seen masses of admirable consistency prepared by this simple 

 method. 



310. Hyatt's Shellac Method (Am. M. Micr. Journ., i, 1880, p. 8 ; 

 Journ. Roy. Mic. Soc., iii, 1880, p. 320). Prepare the object by soaking 

 in alcohol, and then put it for a day or two into a clear alcoholic solution of 

 shellac. Take a cylinder of soft wood, split it, and make a groove in one or 

 both of the half-cylinders sufficiently large to admit the object without 

 pressure. Imbed in the groove with plenty of thick shellac solution, and 

 tie together the two halves of the cylinder with thread. In a day or two 

 the shellac will be quite hard ; the cylinder is then fixed in a microtome, is 

 soaked with warm water, and sections made. Should the shellac prove so 

 opaque as to interfere with a proper examination of the sections, a 1 drop of 

 borax solution will immediately remove this difficulty. 



This process is intended for the purpose of making sections through hard 

 chitinous organs consisting of several pieces, such as stings and ovipositors, 

 retaining all the parts in their natural positions. 



311. Von Koch's Copal Method (Zool. Anz., 2, vol. i, 1878, 

 p. 36). Small pieces of the object are stained in bulk and 

 dehydrated with alcohol. A thin solution of copal in chloro- 

 form is prepared by triturating small fragments of copal in a 

 mortar with fine sand, pouring on chloroform to the powder 

 thus obtained, and filtering. The objects are brought into 

 a capsule filled with the copal solution. The solution is now 



