38 THE AMERICAN MONTHLY [Feb 



of 216 2-3 by 125 mm. The xylem of the bundle lies 

 next to the flat side of the leaf. The cells on the outer 

 edge of the phloem are flattened and have very thick 

 walls. Through both xylem and phloem are rows of 

 parenchymatous cells which form medullary rays, fig. K, 1. 

 These rays in the xylem contain starch, but in the phloem 

 they contain protoplasmic substance. In the xylem next 

 to the fibrous tissue are groups of spiral vessels. These 

 cells have thicker walls and are more rounded than the 

 other cells of the xylem. In studying the fibro-vascular 

 bundles double staining with eosine and gentain violet is 

 most profitably employed. The phloem is stained red and 

 the xylem is stained a beautiful blue. — University of 

 Tennessee. 



Practical Hints on Mounting. 



By R. G. MASON. 



We take for granted that the worker is provided with 

 the following apparatus and materials. Turntable, 3 X 

 1 glass slips, thin glass covers of various sizes (5-8in. and 

 3-4 in. are the most useful), tin cells, a couple of sable 

 pencils, (writer's lining pencils are the best), a bottle of 

 good cement, black and white finishing vanishes, two or 

 three wire clips, and two needles fixed in handles. 



Dry Mounting and Cell Making. — By mounting dry is 

 always understood that there is no medium, used between 

 the object and the cover glass. Objects mounted dry are 

 always placed in a cell: of such objects, those most suit- 

 able for this method are micro-seeds, vegetable hairs at- 

 tached to their leaves, skin of sole, and Foraminifera. A 

 cell must be of sufficient depth for the cover glass to clear 

 the object, but at the same time not be too high. It 

 iust clearing the surface of a specimen enables a higher 

 power to be used if required. 



To make cells, take a 3 X 1 slip, centre it on the turn- 

 table, spin it round at a moderate speed, charge your 



