ZOOLOGY AND BOTANY, MIOKOSCOPY, ETC. 
409 
The simplicity and rapidity of the method is seen when pieces of 
tissue are to be examined. Small pieces as fresh as possible are placed 
for about ten minutes in the methylen-blue solution, they are then well 
washed in a half per cent, salt solution and then examined at once 
in the picro-glycerin, the time required for all the manipulation being 
about 30 minutes. The results as to the positive and negative pictures 
attained by this procedure are equivalent to those produced by the action 
of silver nitrate on fresh tissues. Hence this method has all the advan- 
tages without any of the disadvantages of the silver method. 
Technique of Golgi’s Staining Method.* — The many recent modifi- 
cations of Golgi’s method of staining nervous tissue have tended, says 
Dr. E. Sehrwald, either towards improving the excellence of the picture 
or towards rendering the preparation permanent. But in effect these 
modifications practically destroy the picture, the finer details, visible 
enough in the silver solution, being lost during the manipulations 
required by the various modifications. 
The author proposes a method which leaves intact all the details of 
the original silver chromate deposit and allows the preparation to be 
soaked in warm paraffin, so that sections of any required thinness may 
be prepared. This method simply consists in saturating all the reagents 
employed in Golgi’s method with bichromate of silver. The only 
precaution required is that the reagents should be saturated with the salt 
at a high temperature. 
In this discursive disquisition no details are given, the author, after 
minutely describing a long series of failures, contenting himself with a 
piece of general advice and stating that if this method be adopted pre- 
parations will be obtained which, if they have any fault, are too full of 
detail. 
Method for Restaining old Preparations.! — Mr. J. W. Gatehouse 
gives the following method by which it is possible to stain objects that 
after mounting in balsam have become so transparent as to be scarcely 
visible. Take filtered oil of turpentine and saturate it with picric acid, 
adding the acid gradually till a fine yellow colour has been obtained, 
and scales of the acid remain undissolved. To this solution add care- 
fully crystals of resublimed iodine, taking care to add only a few at a 
time, as otherwise the chemical action set up may possibly produce 
sufficient heat to ignite the turpentine and cause even a slight explosion. 
With all due care even, a series of small decrepitations may be noticed 
as the iodine dissolves. Sufficient iodine should be added to change the 
colour of the solution from a light yellow to a distinct brown tint 
Then place the slide in a dish containing turpentine, to which some of 
the stain has been added, and allow it to remain there until the balsam 
is softened and the stain has penetrated and done its work, when the 
turpentine can be replaced by more balsam. In this way the author has 
restained slides of embryonic tissues which had been mounted several 
years and which had become almost invisible except in special lights. 
After two days’ soaking the whole of the structures were brought out 
splendidly, every detail being perfectly clear. 
* Zeitschr. f. Wiss. Mikr., vi, (1889) pp. 448-56. 
t JoiuD. Microscopy and Nat. Sci., iii. (1890) pp. 113-4. 
