E. S. Salmon and H. Wormald 7 



fungus seen on the exterior and indicates that it is possible to obtain 

 a pure culture directly by transferring fragments of infected wood to 

 a culture medium. 



The medium used in these primary cultures was a decoction of 

 prunes containing 1| per cent, agar and although it was found to be 

 quite suitable for vegetative growth, no reproductive bodies were 

 produced under those conditions. Sub-cultures made on sterilized 

 cylinders of potato in Roux's tubes and on slabs of wood (obtained 

 by making transverse slices^ of a branch from a fig-tree) placed in Petri 

 dishes and autoclaved at 115° C. for 30 minutes, readily produced 

 pycnidia and "tendrils" of conidia. On potato the pycnidia were 

 numerous and in some cases well-developed "tendrils" emerged, while 

 in others the conidia accumulated at the mouth of the pycnidium in 

 a globular mass, the latter condition obtaining when the moisture within 

 the tube was too great for the typical tendrils to retain their characteristic 

 form. The "tendrils" and globules of conidia were at first of an orange 

 colour changing later to a dark red. The conidia were similar to those 

 obtained originally directly from the canker in their size, shape and 

 guttulation. 



On the slices of fig wood the fungus grew vigorously as a white 

 mycelium and eventually produced a few scattered "tendrils": the 

 latter were larger (stouter and usually longer) than those normally 

 produced under natural conditions and were dark red in colour, the 

 conidia however were similar to those obtained from the canker itself. 

 It is interesting to note in this connexion that the "tendrils" were 

 more numerous on the under surface of the wood, i.e. where it came in 

 contact with the inner surface of the Petri dish, than on the upper 

 free surface. 



Inoculation Experiments on Fig-trees. 



Young fig-trees in pots were obtained for inoculation with pure 

 cultures of the Phoma and were kept in a greenhouse throughout the 

 experiments. 



Experiment I. In this preliminary experiment a plate culture of 

 the fungus was started on June 8, 1914 as a sub-culture from one of the 

 tube-cultures mentioned above as obtained from a "poured plate" 

 of conidia. At the end of eight days (June 16) there was sufficient 

 mycelium for use in the following inoculations : 



^ These slices were 4-5 cm. diam. and about 1 cm. thick. 



