The fresh retina is left for two or three days in a mixture 
Bichromate of potassium {}, y^ - - 4 parts 
Osmic acid{\%), ----- i part. 
It is next placed in nitrate of silver solution (^%) 24-30 hours. 
The sections are cleared in oil of cloves and mounted in 
damar. 
Cell Division.— Rabl' recommends the following method 
of preparation for the study of the caryokinetic phases in 
Triton. 
The larvae are treated with chloride of platinum (,'„ -\%) 
24 hours, then thoroughly washed in water, and slowly hard- 
ened in alcohol. The floor of the mouth and the gills are then 
cut out, stained in Delafield's haematoxyhn, or Czokor's alum 
cochineal, a^id examined in methyl alcohol. In media of higher 
refractive index the finer details are not seen. The prepara- 
tions last only for a few days. 
Demonstration of the ToNOPLAST.-Professor Vries^ has 
shown that the vacuoles of plant cells represent organs with 
distinct and very resistant walls. In harmony with its func- 
tion the wall is called the tonoplast Aleuron granules are 
tonoplasts with their contents in a dried condition. The 
demonstration of the tonoplasts is accomplished by a 10% 
solution of nitric acid reddened with eosin. The method may 
prove useful in the case of animal as well as plant cells. 
The Preservation of Actinia.'— The preservation of 
Actinise in a suitable condition for future study is a matter of 
some difficulty, and has greatly hindered a thorough study of 
the group. The great difficulty experienced m killing the 
animals sufficiently rapidly to prevent contraction is the main 
obstacle, and the method of first producing torpor by the use 
of chloroform or nicotine, as practiced by the Hertwigs ( 79), 
is tedious and not always successful. I was in hopes that good 
results might be obtained by the use of cocaine, but my 
it gave negatn 
results. The success of any 
method depends greatly on the character of the form under 
» Hugo de Vries. Intracellular Pangenesis, 1889, 
8 J. Playfair McMarrich, Actiniaria of the Baham 
