66 ACROTHECIUM PENNISETi 
These data show that this fungus prefers a reaction ranging between+5 
and +10 Fuller’s scale, but can withstand a considerable range either way. 
6. ETIOLOGY OF THE DISEASE. 
(a) Formal proof of pathogenicity of Acrothecium Penniseti n. sp. There is 
no doubt that this disease on bajra is due to this fungus as determined by 
the following points :— 
1. The constant association of the fungus with the disease, and its 
isolation from typical diseased tissue of the host. 
2. Healthy plants inoculated with pure cultures give characteristic 
signs of the disease. The penetration of the fungus was also noticed. 
3. The fungus was reisolated from inoculated diseased spots and reiocu- 
lated on healthy plants and the disease was produced as before. The reisolated 
fungus was compared in culture with the fungus used for inoculation and was 
identical with it. 
(b) Details of inoculations. The following are the details of the 
inoculations made on leaves and ears of Pennisetum typhoideum :-— 
Experiment 1. In the beginning of September 1919, 26 inoculations were made by 
placing a little mycelium and spores from a pure culture on either side of a 
number of leaves and leaf-sheaths ; these were kept in a moist chamber. After 24 
hours almost all the leaves were discoloured and had become pale in the places 
where they had been inoculated, and after 48 hours on microscopic examination it 
was found that the mycelium had penetrated in the tissues. Conidiophores and 
conidia started coming out after 72 hours. The infected spots gradually increased 
in size and were like those found in the field. 
Experiment 2. (15-9-19.) Nine leaves of a healthy shoot were inoculated on either 
side with spores and mycelium from a pure culture as already described. and 
the shoot was covered with a bell jar. A control was also kept. On the fourth day 
four leaves showed signs of infection in the inoculated places ; another spot appeared 
on the sixth day ; two more on the seventh and the remaining on the eighth day. 
In the beginning the infected spots became pale and then gradually turned yellowish 
brown and ultimately dirty brown. All the spots increased in size and in five or six 
days after infection conidiophores began tocome out. The control was intact. 
Experiment 3. (15-9-19.) Two healthy shoots with ears were inoculated in six places 
on leaves (either side) and in eight places on ears. A control was also kept. In this 
experiment one leaf took the infection within 48 hours, and onthe fourth day three 
more showed infection. On the sixth day the remaining leaves were also found to be 
infected, showing the characteristic symptoms of the disease. All the inoculations 
made on spikelets of the ears were successful and the glumes became light brown. 
Conidiophores began to appear eight days after inoculations. The control was 
healthy. 
Experiment 4. (18-9-19.) Twelve leaves and sheaths of a healthy young plant (about 
two months old) were inoculated on either side with spores and mycelium from 
