[Vor. 1 
306 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
Cellulose agar was made by adding about one per cent (esti- 
mated by the weight of the paper before treating with Schwei- 
zer's reagent) of precipitated paper cellulose, prepared as stated 
above, to а mineral nutrient solution, the complete medium 
having the following composition: 
Monopotassium phosphate, 1 gram \ 
Magnesium sulphate, 1 gram 
Sodium chloride, 1 gram 
Ammonium sulphate, 1 gram 
Calcium carbonate, 2 grams 
Tap water, 1000 ec. 
The insoluble precipitate appearing in the mineral nutrient 
solution was filtered off before the cellulose suspension and agar 
were added. Good results were also obtained by using 0.5 
gram of calcium nitrate instead of 2 grams of calcium carbonate, 
in which case filtering is unnecessary. The mineral nutrient 
solution having the composition tabulated above will be referred 
to as nutrient “А.” 
Another nutrient solution very low in organie matter was 
also employed in the cellulose agar, but with rather unsatis- 
factory results. This solution, which will be referred to as 
nutrient “В,” is that employed by Reed (42), and is made up 
as follows, the only organic material present being the small 
amount of sodium citrate: 
ее 10 grams 
Dipotassium phosphate....................... 5 grams 
Magnesium вйірһа4е......2................... 1 gram 
SO Белі Т ТЕСТ КГ ЯМЕН ЕЕ 1 gram 
(bn co а ыса ye eighteen с с, 1000 cc. 
In making the cellulose agar this nutrient solution was used in 
exactly the same way as nutrient “А.” 
Since previous investigators have held that the celluloses from 
various sources differ in their resistance to hydrolyzing enzymes, 
an attempt was made in this investigation to prepare a cellulose 
from a natural host—plums—of the parasite. In order to secure 
a cellulose that is modified as little as possible in the process 
