828 N. H. MOSELEY. 



provokingly all over the slide on the removal of the im- 

 bedding substance by benzine, oil of cloves, &c. The imbed- 

 ding substance made use of by Mihakowics consists of a 

 jelly composed of equal parts, by weight, of glycerine and 

 gelatine. The glycerine is heated in a warm bath, and the 

 gelatine dissolved, in it. An extremely tenacious jelly is 

 the result. I found this jelly too tough for use with corals, 

 and I added a larger proportion of glycerine. The tenacity 

 of the jelly can be modified to any extent according to the 

 nature of the substance to be cut, just as the consistence 

 of the oil and wax mixtures is varied to suit the tissue to be 

 imbedded; but it must be remembered that the less tenacious 

 the jelly, the more it will shrink when placed in absolute 

 alcohol. Mihakowics stained his hardened embryos, then 

 placed them in absolute alcohol, and, just before putting 

 them in the imbedding substance, placed them for a minute 

 in water in order to avoid great shrinking, which otherwise 

 occurs. I hardened my corals in chromic acid, absolute 

 alcohol, or osmic acid, decalcified them in weak hydrochloric 

 acid, and then soaked them in glycerine, previously staining 

 those hardened in absolute alcohol. The corals were trans- 

 ferred directly from the glycerine to the warm jelly. I 

 found that the jelly more thoroughly penetrated the spongy 

 tissues when they were thus previously soaked in glycerine. 

 The imbedding jelly is kept just fluid over a water bath, 

 and the small masses of tissue are macerated in it for one 

 or two hours until all their interstices are thoroughly per- 

 meated by the warm jelly. In the case of corals, which, by 

 the removal of the supporting calcareous skeleton become ex- 

 cessively spongy, it would be well, no doubt, to place the vessel 

 in use under an air pump for a short time. There was, un- 

 fortunately, no air pump available on board H.M.S. Chal- 

 lenger. When the tissues have been well soaked in the 

 jelly they are transferred, together with a portion of jelly, 

 to small cavities scooped out in small blocks of liver which 

 has been hardened in ordinary alcohol, and are arranged in 

 the proper position for cutting, and the cavities filled up 

 with the jelly. When the jelly has set, which condition 

 most rapidly ensues, the blocks of liver are placed in abso- 

 lute alcohol, and allowed to remain there two or three days. 

 The jelly becomes hard, white, and opaque, and the liver 

 hardens, and shrinking around it holds it firmly. The liver 

 and hardened jelly are now cut into sections in the ordinary 

 way with a razor, wetted with absolute alcohol, and the 

 sections are treated with glycerine upon the slides. The opaque 

 jelly becomes in a few minutes perfectly transparent, and is 



