132 Wager . — Observations on the Structure 
means of the microtome. These were mounted at once in 
Canada balsam. 
The best preparations were made however by staining the 
sections, when cut, on the slide. The method of preparation 
was the same as in the above case, except the staining en bloc , 
which was left out. The sections were cemented to the slide 
with a solution of white of egg and glycerine. The paraffin 
wax was then melted by heating the slide on a water bath, 
and washed off in turpentine. The slide was next placed 
in absolute alcohol, and was afterwards transferred to the 
staining solution. The best staining solution was found to 
be a dilute solution of Kleinenberg’s haematoxylin in water. 
This was made by adding a few drops of the strong haema- 
toxylin-solution to a beaker of water until the whole was 
decidedly coloured. The sections were left in this until they 
were considerably overstained, and were then placed in a 
dilute solution of acid alcohol for a short time to reduce the 
stain. The acid alcohol solution was only just strong enough 
to reduce the stain slowly. It was made by adding a few 
drops of strong hydrochloric acid to a beaker of 70 per cent- 
alcohol. The sections were then washed successively in 70 
per cent., 90 per cent., and 100 per cent, alcohol, and were 
next transferred to turpentine until quite clear and transparent 
(a few minutes were found to be sufficient for this), and were 
finally mounted in Canada balsam. The preparations thus 
obtained, owing to the thinness of the sections, which were in 
many cases only about the. g wo of an inch in thickness, 
exhibited the structure of the nucleus clearly and distinctly. 
It was found to be quite possible to distinguish the nuclei 
without the use of staining reagents, especially in sections of 
alcoholic material when mounted in glycerine. The nuclei 
presented the appearance of bright refractive bodies, which 
could be easily distinguished from the surrounding granules. 
It may be pointed out here that Zalewski 1 describes the 
nuclei in the oospore of the allied genus Cystopus , in the 
1 Bot. Centrbl. xv, 1883. 
