110 



THE AMERICAN MONTHLY 



[May, 



and manifest certain of the protoplasmic powers in so high a de- 

 gree as to nearly exclude the others, but retaining the two most 

 universal powers of protoplasm — metabolism and reproduction. 



EXPLANATION OF PLATE. 



(All figures were drawn with the Camera Luclda.) 



Fig. I. Surface view of tuber, showing the 

 law of position of the buds, x 73 natural size. 



Fig. 2. Vertical section of the stem through 

 a bud, i-howing the bud with iis terminal por- 

 tion at/', and its leaves at a, with the thin 

 layer of bark and the pith in which, parallel 

 with the bark, lies the fibro-vascular layer. 



Fig. 3. Vertical section of stem magnified 

 133 diameters, showing (i) the bark cells at c 

 in rows, the edges of which produce the par- 

 allel lines seen in the surface view (I'ig. 4); 

 (2) the living subdermal cells specialized as 

 starch producers. The uppermost are fidl of 

 protoplasm (at d in the figure); below them 

 are cells containing large vacuoles and in which 

 the starch grains are forming (cf. figs. 7, 8,9). 

 There are only a few rows of these before the 



cells filled with starch are reached at st in the 

 same figure. 



Fig. 4. Surface view of the bark cells mag- 

 nified 133 diameters. 



Fig. 5. Flat view of cells immediately be- 

 low the bark from the level marked d in fig. 3. 

 After treatment with weak acid these cells, 

 before irrigation of the acid, appeared to be 

 absolutely empty. 



Figs. 6, 7, 8. Greatly enlarged views of nu- 

 cleus and surrounding protoplasm from cells 

 at level of e in fig. 3, showing the starch 

 granules surrounded by the protoplasm in dif- 

 ferent stages of formation. 



Fig. 9. Section magnified 240 diameters, 

 showing the fibro-vascular bundle with its 

 spiral cell and the cylindrical cells on either 

 side. 



The Decolorization of Preparations Stained with Osmic 

 Acid. — The staining power of osmic acid is very great, especi- 

 ally over the fat cells, and even with a very dilute solution it is 

 very easy to overstain. Peroxide of hydrogen in dilute alcoholic 

 solution will, to a certain extent, remove the excess of staining 

 matter. The proportion of commercial hydrogen peroxide is i 

 part to 8 or lo parts of alcohol, and 3 to 5 parts of distilled water. 

 The bleaching fluid should be prepared only as needed. — Pacific 

 Record. 



o 



Shimer's New Mounting Medium. — This is made of equal 

 parts of Farrant's solution, glycerine, and glycerine jelly, the 

 last being made of gelatine, 30 parts ; water, 70 parts ; glycerine, 

 100 parts; carbolic acid, 2 parts. Of this jelly, liquified by the 

 aid of a water-bath, pour i fluid ounce into a 4-ounce glass-stop- 

 pered bottle ; add an equal volume of the Farrant's medium and 

 of glycerine. Agitate, thoroughly mix, and add a small lump 

 of camphor. A little warming is necessary to make it fluid for 

 use. — Pacific Record. 



Ink for Writing on Glass or Porcelain. — The Rutidschau 

 (Prag.) gives the following: Dissolve in the water-bath 10 parts 

 bleached shellac and K^ parts Venice turpentine in 15 parts of oil 

 turpentine. Incorporate in the solution 5 parts of lamp-black. 

 So-called diamond ink for writing on glass is a compound of 

 fluoric acid and barium ; the latter has no eflect, it being simply a 

 white powder to give body to the acid. The ink can be used with 

 a rubber hand-stamp, and it should be allowed to remain fifteen 

 minutes, when the barium will brush ofl', leaving the design on 

 the glass. — Nat. Dr7ig. 



