ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



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for cutting sections of fresh tissue without imbedding, of tissue frozen 

 by means of ethyl chloride, and of material imbedded in paraffin and 

 celloidin. 



In fig. 45 the instrument is shown with ratchet and pawl adjust- 

 ment, with clamp for paraffin block, and apparatus for freezing with. 



Jxiu 



Fig. 4G. 



ethyl chloride. In fig. 46 the instrument is shown with obliquely 

 placed knife, the position adapted for cutting celloidin sections and 

 fresh hard objects. The apparatus is well supplied with the accessories 

 necessary for fixing and holding the objects to be cut, and knives 

 suitable for sectioning according to the method of imbedding. Full 

 directions are given for manipulating the machine, how to set and strop 

 the knives, and the best way to fix the knife for cutting. 



Sectioning Fresh Plant-Tissues.* — N. B. Pierce presses a small 

 piece of leaf or other like tissue between two flat cakes of paraffin, each 

 being 20 mm. long, 14 mm. wide, and 8 mm. thick, taking care that the 

 margins of the blocks coincide. A heated scalpel is then run round 

 the edges of the blocks so as to melt them together where touched. 

 The block is then cooled in water until it is sufficiently firm to be fixed 

 to the microtome block and trimmed in the usual manner. In this 

 way excellent sections, 5 fj. thick, can be obtained of perfectly fresh 

 tissue. 



Improvement in Reichert's Sliding Microtome.f — J. Starlinger 

 describes this new arrangement, which is clearly recognisable from 

 fig. 47. It concerns the mechanism of the knife-slide and is intended 

 to make it independent of the direction of gear rotation. Hitherto, 

 the windlass H and chain have been in intimate connection, and every 



* Journ. App. Micr.. v. (1902) pp. 2074-5. 



f Zeitechr. f. wiss. Mikr., xix. (1902) pp. 145-7 (1 fig.)- 



