72 



ANATOMICAL TECHNOLOGY. 



A. A tracer may be made by any one from a piece Of steel rod, or from a dental ' ' exca- 

 vator," but the saving so eflfected is hardly wortb tbe trouble. The instrument is made by 

 Codman & Shurtleff, and perbaps by others. 



B. The tracer is apparently similar to the "seeker" of the English anatomists, and the 

 "finder " of the Germans. The instrument was introduced into the laboratory of Cornell 

 University with a microscope presented by the late Hon. John Stanton Gould. The con- 

 version of the opposite end into a tapering probe was suggested by Mr. Willis N. Rudd, a 

 student, and the sharpening of the concavity was first proposed by the junior author. 



§ 167. Trays— Fig. 78. — These are usually made of stout tin, but 

 copper is more durable. If wood is used, it should be thoroughly 

 oiled. A wire loop should be soldered at the middle of each end, 

 and on each side at about one-sixth of the distance from each end. 



Four sizes of trays are convenient in the dissection of cats : 

 15 X 20, 20 X 30, 30 x 40, and 40 x 60 cm. The depth of the two 

 smaller sizes should be about 1 cm., and that of the two larger 

 about 2 cm. The largest size should be stiffened by diagonals upon 

 the bottom. 



§ 168. Tripod Magnifier— Fig. 26. — This is a simple magnifier 

 with a large field, and mounted upon a tripod which may be placed 



"!l 



ISp.c. 

 Qlyeerin 



Fie. 36.— Tkipod Magnifier ; x 1 ; § 168. Fig. 27.— Wettikg Bottle ; § 170. 



in liquid. While examining delicate objects out of liquid, it is 

 safer to turn the legs toward the eye, or remove them altogether. 

 The object should be held so as to receive the best light. 



§ 169. Tunnels. — Several sizes are desirable, of both glass and 

 tin. The latter should have the slender part fluted. When the 

 larger part of a tin tunnel, or either part of a glass one, is set into a 

 bottle or jar, a thick string should be interposed between it and the 

 mouth of the vessel to permit the escape of air as the liquid enters. 



