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George Arnold 
then only in the central parts of the pieces of tissue, where the fixation 
is poor in regard to the other parts of the cell. The reason for this is that 
these two fixatives contain a large proportion of acetic acid, which has 
a solvent action on the substance of which the chondriosome is composed, 
as has been proved by the researches of Mayer, Faure-Fremiet & 
Schaeffer (1909). On the other hand, the presence of osmic acid is al- 
most essential for the successful demonstration of that body. 
Benda’s modification of Flemming’s solution is made up asfollows: 
15 ccs aqueous solution 1% chromic acid | with 3 — 5 drops glacial 
4 ccs aqueous solution 2% osmic acid J acetic acid. 
The material, cut into pieces of not more than 2 cubic mm, was left 
in the fixative for twenty four hours, then washed in running tap water 
for one and a half liour, and dehydrated quarter hourly in grades of alcohol 
from 20 % upwards, increasing by 10 % at a time, up to the absolute al- 
cohol, followed by cedarwood oil and paraffin (45° C.) and then embedded. 
The four following stains were employed. 
(1) Heidexhain’s Iron-alum and Haematoxylin, followed by Thionin 
and Orange G. 
(2) Thionin and Orange G. 
(3) Altmann’s Acid Fuchsin, for tissue fixed in the potassium bichromate- 
osmic acid solution. 
(4) Saffranin-Methylene blue and Orange G. 
The specific stains for ehondriosomes are, 1. Bexda’s Oystal Violet 
and Sulfalizarinate of Sodium 1 ), 2. Altjiaxn’s Acid Fuchsin solution, and 
3. Heidenhain’s Iron Alum and Haematoxylin. In the use of the last, 
the sections should be immersed for 24 hours in 4% Iron- Alum solution, 
followed by 0.5% Haematoxylin, aqueous solution, for from 12 to 24 
hours, and differentiated with Iron-Alum again. 
The disadvantage of this stain is that it stains the nuclear structures 
equally with the ehondriosomes. However, by a modification of the pro- 
cess, it is possible to differentiate the two sorts of structures. The method 
is as follows. The sections are allowed to remain for 24 hours in a 6% 
solution of Iron-Alum, they are then rapidly rinsed in tap water, and then 
immersed in a 0.5 % aqueous solution of haematoxylin for six hours. They 
are then differentiated with a 4 % solution of Iron-Alum, until the nuclei 
are of a verv pale grey colour and the ehondriosomes of a grey-black tint. 
*) This was not used. An account of the method is to be obtained in a paper 
by Meves and Duesberg. Die Spermacvtenteilungen bei der Hornisse. Arch. f. Mikr. 
Anat. Bd. LXXI. 1907. 
