270 
The diseased plants had been grown from seed and had not been 
disturbed in any way. 
The most characteristic symptom of the disease under 
discussion was the softening of the hypocotyls of the attacked 
seedlings, the tissues of which were, in cases, so completely 
disorganised that they collapsed under easy pressure or broke 
when a pull was exerted to remove the diseased plant from the 
soil. This Sears aan was analogous to that found in carnations 
affected with the same wilt disease and it doubtless gave rise 
to the alternative name ‘ crown-rot,’ which has been used by 
van der Bijl in South Africa.* It likewise led the writer to 
presume the cause of the disease to be similar to, if not the same 
as, that of the carnation wilt, viz., a species of Fusarium, although 
at the moment no Fusarium mycelium or conidia such as were 
found externally on wilted carnation plants could be found on 
the diseased plants under examination. The leaves of affected 
plants withered and fell off. Owing to the breaking down of the 
cortical tissues, the roots, especially the smaller, were usually 
soft to the touch. While the lower part of the hypocotyl might 
be rotten, the upper portion of it might be quite firm. Micro- 
scopic examination of sections of the latter showed the cells of 
the parenchyma to be unaltered and full of starch, while sections 
of the firmer parts of the former showed the presence of mycelium 
in quantity. Good preparations were obtained from both hypo- 
cotyls and roots by staining with haematoxylin and alcoholic 
eosin, as recommended by E. J. Durand, after killing in Durand’s 
modified Gilson’s mercuric chloride solution and clearing away 
the usual brown discolouration in a saturated aqueous solution 
of chloral hydrate. Hyphae were found in the bundles of the roots, 
but their choking of the vessels was never complete enough to 
account for the wilting and death of the plants. In fact, they 
were always much more plentiful in the root cortex and in the 
starch cells of the parenchymatous tissues of the hypocotyl. 
At times the body of a cell of the latter would appear to be a 
tangled mass of hypae. The hyphae resembled very markedly 
those found in sections of wilted carnations and described as 
followst by the writer—‘‘ This internal mycelium varied in 
thickness, was much branched, and was seen to pass freely from 
tracheids to parenchyma without constrictions. The main 
hyphae in a tracheid would give off numerous slender branches 
which could be followed as they penetrated the pits.” Where 
hyphae were present, no cell-contents or stored material such 
as starch could be seen, and it is conceivable that the effects 
of the fungus are more of an organic character leading to starva- 
tion or of a toxic character leading to poisoning than of a physical 
character leading to a mechanical choking of the ducts. A 
certain amount of blackening of diseased root or ee 
* Ann. Appd. Biology, ii, 267, 1915-16, 
} Phytopathology, 1. 120. 1911. 
t loc. cit., p. 321. 
