900 



SUMMAEY OF CURRENT RESEARCHES RELATING TO 



By this arrangement objects can be easily frozen, and without any 

 slop. 



The imbedding medium is composed of: — gum arabic, 5 parts; 

 gum tragacantb, 1 part ; gelatin, 1 part. The mixture is dissolved in 

 enough warm water to give it the consistency of thin jelly when cold. 

 A little glycerin (1 : 6) is added to the water. 



Eternod's Microtome with Triple Pincers.* — The instrument of 

 Dr. A. Eternod consists of a brass cylinder terminating above in 

 a polished nickel-plated platform, on which the razor is directed. 

 The cylinder is composed of two drums screwed one over the other 

 so that the lower drum being fixed, if the upper drum is turned 

 round its axis it is gradually raised. The edges of the upper drum 

 are divided into 100 parts. Each entire revolution of the drum 

 raises or lowers the platform 1 mm, ; if it is moved through only 

 one division, the platform is displaced to the extent of 1/100 mm. 



The object is fixed in the axis of the microtome by a triple pincer 

 consisting of three pieces of brass set on the base-cylinder, which can 

 be separated or approximated by means of a screw beneath the in- 

 strument. If the screw is turned from right to left, the three pieces 

 are separated and the specimen can be interposed, imbedded in cork, 

 elder-pith, &c. If the screw is now turned from left to right, the 

 pieces are approximated, and the specimen can be firmly fixed. It is 

 easy with this microtome to cut sections 1/200-1/400 mm. thick. 



Dr. A. Eternod, in writing | to claim to be the originator of the 

 microtome, points out several advantages not noticed in the above 



description. It can be filled with alcohol or 

 Fig. 217. other liquid, so that the object to be cut can be 



preserved for some time. Objects 4 cm. long 



can be cut. 



Gannett's Dripping Apparatus, t — Dr. C. S. 

 Minot recommends Dr. W. W. Gannett's drip- 

 ping apparatus for cutting under alcohol (fig. 

 217). A litre bottle is convenient in size, and 

 the height of the stand should be such as to 

 bring the end of the 



^ 



dripping-tube about 1 in. 

 above the blade of the 

 knife, on which the 

 alcohol is allowed to 

 fall continuously. To 

 regulate the flow an 

 1/8 in. globe-valve is 

 found to be the most 

 convenient. 



Staining for Microscopical Purposes.§ — In further continuation 

 of his excellent articles, Dr. H. Gierke deals with (1) the treatment 



* Journ. de Microgr., ix. (1885) pp. 171-4. t Ibid., pp. 264-7. 



1 Amer. Natural., xix. (1885) p. 916 (1 fig.)- 



§ Zeitsclir. f. Wiss. Mikr., i. (1884) pp. 497-557, and ii. (1885) pp. 13-3G. 



