INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC 



769 



of wliicli pass under the plate 6, aud exert a counter pressure. Botli 

 the specimen and the microtome are thus held in the same manner as 

 one holds the specimen when no section-cutter is employed. The 

 plate and imbedded specimen are pushed gradually forward by turning 

 the milled head of the screw d. 



The imbedding mass employed by Dr. Eoy is the well-known 

 mixture of white wax and olive oil (equal parts by weight for warm, 

 with a larger proportion of oil for cold weather) used with small 

 oblong moulds of zinc without bottoms (instead of the usual paper 

 boxes). They have the convenience of giving a cast suited to the size 

 of the plate on which it is to rest. If the specimen is not imbedded, 

 a pallet of wax or of wax and oil is placed between the tissue and the 

 cork plate so that the edge of the razor may not come in contact with 

 the latter. 



Woodward's Oblique Illuminator.* — Colonel Woodward has de- 

 vised an apparatus, to which he gives the above name, intended to 

 * ' Am. Quart. Micr. Joiu-n.,' i. (1879) p. 268. 



