94 
Mottier.—Chondriosomes and the Primordia 
b. Dehydrate and bring into paraffin. 
c. Sections on the slide remain in the mordant (3 per cent.) four to six 
hours. 
d. Rinse with water and stain twelve hours or longer in a one-half per cent. 
aqueous solution of haematoxylin. 
e. Destain with a 3 or 4 per cent, solution of the iron salt, after which 
wash or let stand in water fifteen minutes. Dehydrate and treat with 
clove oil-orange G. When the desired counterstain is reached, remove 
the oil with xylol, and mount in balsam, either with or without 
following the xylol with cedar oil. Care should be taken not to 
let the clove oil-orange G act too long, or the smaller chondriosomes 
may be rendered indistinguishable. 
It will be seen that the latter process is shorter and simpler than 
the former. In some tissues prefer it to the crystal violet method. 
Observations. 
This paper will deal with the results obtained in the study of root-tips 
of Pisum sativum , Zea Mays , the thallus of Marchantia polymorpha , 
Anthoceros , Pallavicinia , the seedling of Pinus Banksiana , the stem and 
leaves of Elodea canadensis , and the root-tip of Adiantum pedatum , together 
with certain Algae. 
Pisum. I began first with the root of the pea in order to verify 
observations of others and to test the usefulness of the methods employed. 
Sections were cut from three to five microns in thickness. 
Pisum proved to be one of the most satisfactory objects for the 
demonstration of the transformation of primordia into leucoplasts. In the 
meristematic cells of the root, at the juncture of the root-cap and the tip 
of the root proper, one finds the structure shown in Plate I, Fig. 2. 
The most conspicuous objects in the cell, apart from the nucleus, are the 
numerous black rods (iron-alum-haematoxylin being used) occurring in 
relatively large numbers. These rods vary in length and thickness ; they 
may be straight or variously curved or bent, while some present a lumpy 
appearance as if composed of granules. In this region of the root some 
of the rods show a globular thickening at one end. The rods sometimes 
show a tendency to accumulate about the nucleus and arrange themselves 
radially from it, but, as a rule, they are promiscuously scattered within the 
cytoplasm. 
In addition to the large rods (Fig. 2) are numerous very small globular 
or granular bodies and very slender, delicate rods that stain the same colour 
and* seem to be of the same ultimate composition as the large rods. The 
granules occur singly or in rows or chains of two or more. The very 
