1888.] MICROSCOPICAL JOURNAL. 69 



Celloidin; its advantages,* 



By J. MELVIN LAMB, M. D., 



WASHINGTON, D. C. 



The patented article, celloidin, comes into the market in the shape of cakes, 

 rather transparent, and looking like ordinary glue. Another form is in small 

 shavings or chippings. This is made from the purest pyroxylon, by E. Scher- 

 ing, Berlin, is non-explosive, free from precipitates, and costs about 3 rn. per 

 cake. 



Inasmuch as a cake dissolved will furnish material enough for embedding 

 100 to 150 average size specimens, it is, considering its many advantages, 

 quite inexpensive. 



It has great advantages for embedding many tissues — and for certain organs, 

 for instance, the eye — results may be obtained which cannot be had by various 

 other methods. To cut sections of the eye, an organ composed of tissues of 

 such varying density, it is desirable to have an embedding mass in which the 

 tissues may be kept in a fluid solution, without injury, until thorough satura- 

 tion is ensured, and which will maintain the various parts of the object in 

 perfect relationship for cutting, and after sectioning. 



For this organ, and for tissues that have no connection of parts — tissues 

 that immediately go to pieces, so that it is impossible to distinguish the rela- 

 tionship of parts — this mass offers superior advantages. 



The use of celloidin is a cleanly process, nothing further being required in 

 its application than a few stoppered specimen jars and some corks for fixino- 

 the embedded objects for cutting. No amount of experience is necessary in 

 its use to insure good results, and it is comparatively rapid in its action. 



In other modes, wax and parafiine specimens must be kept in a moulten 

 mass over a water-bath, maintaining the heat at a certain temperature for a 

 length of time, varying from 6 to 12 hours. Should the heat go above a cer- 

 tain degree, the specimens will be most likely ruined, and if, on the other 

 hand, it falls below the required degree, the process must be repeated. 



The celloidin solution permeates the tissues thoroughly, fixing the parts in 

 their natural position, does not shrink the tissues, and the process can be dis- 

 continued at any time, or delayed any length of time without resulting in harm 

 to the objects. 



It is perfectly transparent, and sections so embedded may be stained and 

 mounted with the embedding material, which takes the staining but faintly ; 

 and when a specimen is cleared and mounted, the foint tinging on the cel- 

 loidin does not detract from the appearance of the section, or in any way 

 interfere with its usefulness. 



Celloidin solution is made by dissolving the chippings in an equal part of 

 absolute alcohol and ether. To four ounces of the above, add sufficient cel- 

 loidin to make one solution of a syrupy consistence ; the second somewhat 

 thicker. Unless kept thoroughly stoppered with ground glass, the solutions 

 will thicken by evaporation of the solvents. A quantity of the solvent serves 

 at any time to reduce the solutions to the desired fluidity. 



Specimens should be brought from absolute alcohol and placed in a mixture 

 of equal parts of ether and absolute alcohol for about 6 to S hours, and then 

 may be carried into the thinner solution. 



Let most objects remain here for 24 hours ; when they are to be removed 

 to the thicker solution, objects can be safely left in either solution for an in- 

 definite length of time, so that for delicate objects in which it is especially 

 desirable to ensure thorough saturation and fixing of the parts in natural rela- 

 tion, they may be left in the solution for some weeks previous to embedding. 



♦Read before the Washington Microscopical Society, Jan. 24, 18 



