F. J. P. SHAW. 127 



Further proof that the ground nut seed may be infected witli 

 Rhizoctonia was afforded by the behaviour of the plant in pot 

 culture. Out of all the cultures of the jute, cotton, cow pea and 

 ground nut made in the course of this research, it was only in the case 

 of ground nut that deaths due to Rhizoctonia infection took place in 

 the control pots. If the deaths in the control pots had been due to 

 soil infection, owing to imperfect sterilisation, it would be expect- 

 ed that similar deaths would also take place in the cultures of 

 jute, which is far more susceptible to the attack of Rhizoctonia 

 than is ground nut. Moreover, the ground nut ripens its seeds 

 below the surface of the ground in the same situation as those 

 tubers (potato, carrot, etc.) which are often badly attacked by 

 Rhizoctonia. 



The morphological features of the Rhizoctonia of ground nut 

 agree exactly with those of cotton and jute. The characteristics of 

 the hyphae in an agar culture 24 hours old are shown in Text Fig. 

 Ill, 5 ; in the case of some diseased plants from Peshawar hyphse 

 with clamp connections were present (Text Fig. Ill, 4). The man- 

 ner of the formation of the sclerotia was studied and is shown in 

 PI. VII, Figs. 1, 2, 3, & 4. In a hypha which is about to form a scle- 

 rotium a large number of transverse divisions take place, so that a 

 number of short barrel-shaped cells are formed which are very rich 

 in oil globules. Some of these give rise to lateral outgrowths, con- 

 sisting of one or two cells, which grow parallel with, and adhere to, 

 the side of the parent hypha. By the constant repetition of this 

 process a mass of parenchymatous cells is formed which eventually 

 becomes the mature sclerotium (PI. IX, Figs. 1, 2); there is some 

 slight differentiation into cortex and medulla, the central cells being 

 large and thin-walled, while the peripheral cells have a smaller lumen 

 and thicker walls. This process agrees closely with that described 

 by Kilhn for sclerotial formation in R. solani. 



Culture work on the ground nut was complicated by the liabil- 

 ity to sow infected seed. On the whole, about 30% of the inocula- 

 tions were successful. In a successful inoculation the stem turns 



