IN OSCILLARIA AND TOLYPOTHRIX. 189 
generaly; and it is only a small part of his whole work with 
which we are directly concerned. To previous work by this 
author we owe a large part of our knowledge of the chemistry of 
the nucleus. 
The method used by him in that part of the investigation 
which is of immediate interest in this connexion was to treat the 
objects first with ether-alcohol to remove fat, and then to digest 
in pepsine solution, subsequently making use of various staining- 
reagents. By this method Zacharias was able to demonstrate, 
both in the cells of Yeast and in those of Oscillaria and Tolypo- 
thriv, the existence of a body having the coarsely fibrous struc- 
ture with which histologists are familiar as characterizing the 
so-called “ knot-stage ” of the nucleus of the higher plants. The 
structure in question closely agreed in its reactions with the fila- 
mentous (chromatin) portion of undoubted nuclei. As we have 
seen, it resisted the action of pepsine, while, on the other hand, it 
was soluble in such reagents as dilute solution of common salt. 
In its staining peculiarities the body in question also showed a 
nuclear character. The tests applied by Zacharias will probably 
be regarded as satisfactorily establishing the existence of a real 
nucleus in each cell of the plants in question. In Zolypothrix 
the body which gives the nuclear reactions is already visible in the 
natural state without any treatment whatever. 
The exhibition now described is confirmatory of Zacharias's 
results; but the methods employed were different. It must 
here be expressly stated that the nominal exhibitor can only 
. claim a very small portion of whatever credit may belong to the 
demonstration. The preparations were made by a lady, Miss H. 
V. Klaassen, working in the Jodrell Laboratory at Kew; and to 
her is due, not only the actual manipulation, but also, to a great 
extent, the elaboration of the methods. The drawings shown are 
also by her hand. 
The plants so far investigated comprise three species of Os- 
eillaria and Tolypothrix coactilis, The preparations actually 
shown were prepared as follows :—“Oscillaria No. 1” was treated 
for five minutes with methylated ether and then stained for four 
minutes with Kleinenberg’s hematoxylin. The specimen was 
then mounted by the usual process in Canada balsam. In the 
middle of each cella deeply stained roundish body is seen which 
has a distinctly fibrous structure, comparable, as already stated, 
to the well-known “knot-stage” of the ordinary nucleus, as 
1 
3 
