914 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



bracket is removed and the glass plate is supported on a tripod, tlie 

 ether apparatus being applied beneath. 



The advantage claimed for the instrument over the older forms 

 is that when only a few sections are required but little ether is 



Fig. 170. 



expended, as they can be frozen in fifteen seconds ; whereas with the 

 Groves-Williams instrument 1 min. to 1^ min. is requisite. The 

 latter, however, has the great advantage of entirely conveying from 

 the room the fumes of the ether, which in many cases cause serious 

 inconvenience to the operator. The instrument is made by Messrs. 

 Swift and Son. 



Improvements in the Thoma Microtome.* — A. Andres, W. 

 Giesbrecht, and P. Mayer describe some improvements in the medium 

 size of this instrument. 



The " clicking arrangement " enables each turn of the micrometer- 

 screw to be recognized by the ear, so that the eye, which is already 

 sufficiently strained by the cutting, rests. This is of importance when 

 working much with the microtome, especially with sections of small 

 objects ; the authors, therefore, do not agree with Prof. Thoma when 

 he says f " such complications are useful only for very special con- 

 ditions." On the author's suggestion Herr Jung has applied this 

 arrangement to the drum of the micrometer-screw, and has further 



* MT. Zool. Stat. Neapel, iv. (1883) pp. 432-5. 

 t See this Journal, ante, p. 303. 



