A. R. Sanderson and H. Sutcliffe 59 



good results. The growth on dolichos agar and on bean agar was much 

 slower than on those previously mentioned, pycnidia however were pro- 

 duced even on these in about 20 days and a fair number of resting spores 

 in the same time. In every case of inoculation of freshly exposed surfaces 

 of bark or wood, infection was set up, and the disease rapidly spread 

 over the entire surface exposed, more particularly when an excess of 

 moisture was present. 



In six cases portions of bark about six inches square were removed 

 from the tree, and the exposed underlying surface inoculated with spores 

 from pycnidia in water. When a considerable number of pycnidia had 

 been produced on all these surfaces and they all showed the character- 

 istic appearance of mouldy rot, jodelite was applied, and the next day 

 a fresh portion of bark removed below, but in continuation with the 

 first surface exposed. In every case the disease appeared on the fresh 

 surface at the end of two days. Discolouration was apparent as a con- 

 tinuation from the previously affected part, the disease having spread 

 downwards in the wood and innermost layers of bark. A similar ex- 

 periment was carried out but fresh surfaces exposed laterally. The 

 disease again spread to the freshly exposed surfaces. 



Many of the cultures on artificial media produced considerable 

 numbers of resting spores embedded in the media well below the surface. 

 These large resting spores are produced in from 8-10 days after inocu- 

 lation, and, being thick walled can withstand considerable desiccation 

 without losing the power to germinate. Some infected material which 

 could not be dealt with at once, was put aside in a desiccator so as to 

 keep it as clean as possible, i.e. to prevent spores of various saprophytic 

 fungi which are almost invariably present in the air from lodging on it. 

 Six weeks later portions of the tissue were taken and infections obtained 

 from resting spores, on stripped surfaces, thus proving that the extreme 

 desiccation to which the spores had been subjected had not succeeded 

 in killing them. They are produced in abundance on the infected surface 

 in dry weather, taking the place of the pycnidia. The third type of 

 spores which so far we have only found in cultures in the laboratory, is 

 very similar in size to the pycnidiospore and is cut off directly from the 

 mycelium. Examination of infected cortical tissue in which the disease 

 had been present 8-10 days showed that large numbers of globules of 

 an oily or fatty nature were present. These varied much in size and were 

 fairly evenly distributed throughout the tissue, which had been killed 

 by the fungus. 



Cortical tissue which had been affected for a considerable time con- 



