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inhibit all growth of the Fusarium. . Again, the viability of the 
conidia of the agar cultures in the presence of formalin vapour 
was tested in hanging-drops. Controls were set up and they 
showed that the macroconidia of all four agar cultures, especially 
those from the prune agar slants, germinated vigorously overnight 
in distilled water drops. Similar sets of conidia were placed in 
distilled water drops over two per cent. and four per cent. 
formalin, and no germination resulted in any of them. The 
spores became shrunken in appearance, and, after only twenty- 
four hours’ exposure to the formalin vapour, refuséd to germinate 
when water was substituted for the formalin. The effect of 
formalin vapour on growing mycelium was also tested in hanging- 
drop cultures and found to be total inhibition of growth and 
spore-production followed by death. 
Experiments commenced with soil fungicides were, owing to 
the seeds being too old, unproductive of results. In any case, 
it should be mentioned that the expense of using in large quantities 
a proprietary article like Fungal would be prohibitive in Uganda. 
It is possible that the only ordinary means of combating the 
Fusarium will be found in continued deep cultivation which might 
succeed in eliminating all the points of origin of the Fusarium. 
Steam sterilisation of infected soil might also be employed, but 
it is impracticable in the majority of cases, and a study of such 
factors as time of planting, water supply and soil texture has not 
been possible. 
THE FusaRiIuM ON GREVILLEA ROBUSTA SEEDLINGS. 
Subsequent to the discovery of the cashew nut wilt, attention 
was drawn to a destructive wilt of Grevillea robusta seedlings in 
adjacent beds. The seedlings were twelve inches or more in 
height and, unlike the cashew nut seedlings, all had been trans- 
planted. On the above-ground parts there was nothing of 
particular note, and the typical soft and sunken area present in 
the cases of the carnation and cashew nut was absent from the 
hard woody Grevillea stems. Many of the smaller lateral roots 
were altogether decayed or denuded of bark and cortical tissues, 
while the tap-roots were still comparatively firm. A histological 
examination, however, of pieces of tap-root showed that they 
were permeated by the fungus, for hyphae, microconidia, and 
chlamydospores were present in the tissues. _ As in the case of the 
cashew nut, mycelium was not found in quantity sufficient to 
choke the elements of the vascular system. In fact, it was far 
more plentiful in the ground tissue. It resembled the internal 
mycelium of the cashew nut and carnation. Conidia were much 
less numerous than chlamydospores, and their connection with 
the hyphae was less plainly seen. The chlamydospores occurred 
singly or in the usual small groups, and were also more numerous 
in the parenchyma cells than elsewhere. Their average diameter 
was 6-74 and they were therefore smaller than those of. the 
Fusarium in culture, but examples of full size were not wanting. 
