196 THE AMERICAN MONTHLY [October, 



To avoid lumpo, which would clog the cannulce, or small vessels, the color 

 is thoroughly ground with the liquid in a mortar. It is stored in a well-stop- 

 pered bottle, and is prepared for use simply by shaking. If permanent prep- 

 arations are not to be made, the mass may be stained by an aniline dye of 

 the desired color. 



Special Mass. — For the injection of brains, and, perhaps, for other rapidly 

 perishing specimens, it seems best, as suggested by Prof. Wilder, to use 

 strong preservatives in preparing the mass : 



Cornstarch (that used for food) , loo c.c. 



5 per cent, aqueous solution of chloral hydrate, .... 50 c.c. 



95 per cent, alcohol, 75 c.c. 



Color mixture, 25 c.c. 



For convenience and economy, a considerable quantity of either of the 

 masses described above may be prepared at once, and kept in a wide-mouthed 

 specimen or fruit jar ; but the mass must be thoroughly stirred before using. 

 The syringe may be filled directly from the jar, and any mass remaining in 

 the syringe after the injection is finished may be returned to the jar. 



If it is desired to have the mass enter very fine vessels, some of the stock 

 mass, as given above, diluted with an equal volume of water or chloral solu- 

 tion, may be injected first, and immediately followed by the undiluted mass, 

 or, for large animals, a mass containing twice the usual amount of starch. 

 In whatever form the starch is used, it is necessai-y to work somewhat expe- 

 ditiously, because the exudation of the liquid in the smaller vessels takes place 

 so rapidly that the mass hardens very quickly in them. The larger the 

 vessel, the more slowly, of course, do the exudation and, consequently, the 

 hardening take place. It sometimes happens that large vessels, like the aorta, 

 are not fully distended after the exudation of the liquid. In this case some 

 mass containing double the ordinary amount of starch can be advantageously 

 injected in two hours or longer after the first injection. 



In animals as large as the cat, and larger, the great veins of the trunk would 

 perhaps better be injected with plaster, as the presence of blood in them pre- 

 vents or greatly retards the hardening of the starch. 



Permanent pj-eparation. — If a permanent wet preparation is to be made 

 of a starch injected animal or part, the cut end of the vessels must be tied in 

 order to prevent the gradual escape of the starch. 



Finally, if vessels injected with the starch mass are dissected free, soaked 

 a day or two in Wickersheimer's preservative, and then dried, they retain 

 their form, and, to a great degree, their flexibility. 



Cornell University, Sept., iSSj- 



REPORTS OF RECENT ARTICLES. 



What is Cancer ? — Dr. Jas. Braidthwaite, of Leeds, England,* seeks the 

 cause of malignancy of epithelial proliferations, while muscular and fatty 

 growths are harmless. He thinks an answer is found in the properties of 

 epithelium-cells they being such that if they proliferate, encapsulation is impos- 

 sible. All epithelium is normally underlaid by a basement membrane 

 which encapsulates it, and, if the growth does not penetrate the basement 

 epithelium, the growth is not malignant. Microscopists, to judge of malig- 

 nancy, study the base of growth. The properties of epithelium-cells to be 

 noted in this connection are : — i. The relative natural hardiness of the cells. 

 2. The rapidity of growth and reproduction. 3. The ordinary mode of 

 death. 4. Existence or not of a natural secretion. 5. Contour of the sur- 



* Laticet, June 30, 18S8, p. 1287. 



