780 Kemp.—On the Question of the Occurrence of 
the required conditions was found to be that adopted by Nemec, namely 
immersion in 0-75 % solution for 1 hr. With this a minimum amount of 
vacuolization and shrinkage of the tissue, together with a maximum specific 
effect of the drug, was obtained. With the stronger solution greater 
vacuolization occurred, and at the same time apparently less specific action 
of the drug. With the weaker solution, although little general disturbance 
of the tissue was caused, the specific action of the chloral hydrate was not 
sufficiently pronounced to give decided results. A weak solution and pro¬ 
longed immersion proved preferable in result to a strong solution and short 
immersion. In many cases the individuals experimented upon were allowed 
to grow subsequently, and their vigorous production of stem and leaves 
indicated that the general health of the plant had not been materially 
affected. With regard to the double series of normal controls, it was found 
that a certain amount of shrinkage and vacuolization occurred in those roots 
which had been subjected to washings previous to fixation, and that these 
features were not seen, or were inconspicuous, in the roots fixed straight 
from normal growth. Fixations were made (1) immediately after poison¬ 
ing, (2) after washing, and (3) after periods of subsequent growth varying 
from 4 hrs. to 70 hrs. or longer. The fixatives used were strong Flemming, 
chrom-acetic-acid, and acetic-alcohol. Strong Flemming was found to give 
the best results, causing less shrinkage of the tissue than occurred with the 
other fixatives, and at the same time leaving its capacity for staining 
unimpaired. It was therefore used in the majority of the experiments, the 
other fixatives being resorted to at need, for comparison. The tissues were 
evaporated down from 10 % to concentrated glycerine, or taken up from 
water through gradually increased percentages of alcohol ; they were then 
taken from absolute alcohol through xylol or cedar-wood oil into paraffin of 
48° or 53° C. melting-point, the paraffin stage being shortened as much 
as was compatible with complete penetration, in order to avoid overheating 
of the tissues. Transverse and longitudinal sections were cut at about 5 n, 
and stained with Heidenhain’s haematoxylin and congo-red, or with 
Flemming’s triple stain. 
The results obtained by this method are in very close agreement with 
those described by Nemec ; and they include, contrary to Strasburger’s 
experience, certain figures in the pea so like those occurring in the hetero¬ 
type reduction of sexual tissue as to be almost indistinguishable from them. 
At the same time these figures present some features which appear to prove 
that they are not reduction-figures at all, but, owing to some peculiar con¬ 
dition of the chromatin, chance to be closely similar to such in appearance. 
The effect of the chloral hydrate is essentially the same in all the tissues 
examined, with the exception of the above figures, which occurred in the 
pea only, and also of certain individual peculiarities which, although perhaps 
insignificant in themselves, are interesting as throwing light upon the nature 
