to the Plant Cell . 
5i5 
again, the deleterious products which arise as excretions arc more highly 
diluted, and hence less harmful to the plants. 
When placed in the culture flasks the solutions were sterilized with 
steam in an Arnold sterilizer. A single heating lasting about forty minutes 
was usually sufficient for the sterilization of the aqueous solutions. 
The media upon which the Basidiobolus was grown require special 
mention. I found that for my purposes an aqueous medium was un- 
satisfactory, and was obliged to add agar agar to all nutrient solutions 
employed. The formula first used is one which is commonly used in 
physiological work with the Fungi : — 
Ammonium nitrate . 
Potassium dihydrogen phosphate 
Magnesium sulphate 
Cane sugar .... 
Distilled water 
Agar agar .... 
1 g- 
o-5 g- 
0-^5 g. 
5 g. 
1,000 cc. 
3*5 g- 
The growth of the fungus on this culture medium was not entirely 
satisfactory, since the palmella stage described by Raciborski (’96) is pro- 
duced when sugar is supplied as a source of carbon. The filamentous stage 
was produced when starch instead of sugar was supplied as the source 
of carbon. I prepared a paste by cooking in an Arnold sterilizer 1 15 grams 
of clean chopped potato in 400 cc. of distilled water. The inorganic salts 
and agar were dissolved in this paste in the same proportions given above. 
This gave a medium upon which Basidiobolus produced good filaments. 
4. Microchemical Methods. 
In examining living cells under the microscope, it was often necessary 
to apply some reagent in order to determine the nature of the substances 
found in the cells. The reagents employed were usually immediately fatal 
to the cells, but they were the best means of showing the nature of sub- 
stances produced under the different conditions of metabolism. It is 
believed that the employment of such reagents gives a more accurate repre- 
sentation of the actual products of cellular activity, than the employment 
of the ordinary fixing and staining reagents. 
Gram’s solution of iodine in potassium iodide was used for identifying 
starch and erythro-dextrin. With the latter it gives a diffuse red-pink 
colour which can be observed microscopically. 
The identification of albuminous substances was rather uncertain when 
the biuret test was used, because the colour was never deep enough to be 
very intense, and hence difficult to observe with the microscope. For 
microchemical work, I found the method described by Loew and Bokorny 
(’89) to be more satisfactory. The method as I employed it was as follows : 
