118 Disease of Olive and Orange Trees. By W. G. Farlow. 
tainly not of fungus, origin. On this gum the fungus grows 
luxuriantly ; and although it may be found on those parts of the 
leaves where no gum can be seen, yet it is evident that it has 
reached such places by growing from the gummy spots. Of the 
origin of the gum, other than that it does not come from the 
fungus, we have no theory of our own to advance. Eemains of 
insects are abundant on the leaves ; but, being entirely ignorant of 
entomology, we cannot say what their relation is to the diseased 
trees. It may be that they are stray visitors caught in the 
gum. The fungus grows most luxuriantly on the remains of 
insects which I have seen, which in some cases present a ludicrous 
spectacle, the hyphae projecting from them like the quills of a 
hedgehog. 
It has often been asserted by botanists that fungi, of the group 
to which ours belong, are particularly inclined to attack trees 
which have been previously infested with insects. In 1849, 
Berkeley, in the London Journal of Horticulture, described a 
fungus occurring in Ceylon on coffee — Triioosporium Gardneri — 
which followed the appearance of a species of coccus which was 
described in the same journal by Mr. George Gardner. In their 
paper on moulds referred to Fumago, Berkeley and Desmazieres 
make the following statement : " They are often, if not always, 
preceded by honey-dew, whether arising from aphides or from a 
sugary excretion from the leaves themselves. Frequently, too, 
they are accompanied by some species of coccus, especially in the 
genus Citrus." Tulasne * does not agree with the writers just men- 
tioned, as will be seen by the reference. He begins his descrip- 
tion of Fumagfo salicina, however, with the following words : 
" Initio fungillus e membranula constat tenuissima, alba, et hyalina, 
matricique vivse instar gummi soluti illitus hseret, quamvis ab 
eadem, maxime si fortuito ea aruerit, frustulatim aliquando se- 
cedat. Id cuticulse struunt utriculi, perexigui, . . . oleo pallido 
tandem repleti," &c. This initial stage described by Tulasne is 
figured in Table xxxiv., fig. 2, mm., 1. c. We must confess 
that the expression " matricique vivas instar gummi soluti illitus 
haeret," seems a little indefinite, but the figure looks exceedingly 
like a collection of oil-globules, or very small eggs. We do not 
* " Quibusdam observatoribus visum est Fumagines in fructicibus potissimum 
provenire quos aphides primum occupassent, tamquam si ex humore dulci quern 
bestiolse istse emittunt, aut ex latice viscido quern matrix ab iis Isesa copiosum 
aliquando stillat, suum pabulum traherent ; necessitates autem hujus modi duplici 
de causa minime verisimiles censemus. Hinc enim sexcenties nobis contigit 
Fumagines luxuriantes videre in arboribus, omnis aphidum generis prorsus experti- 
bus ; illinc Fumagines vere parasitari constat, succis scilicet alienis uti ex his vivis. 
Super hoc argumento conferas tamen quae attulit Berkelseus in tomo iv. (1849) 
Ephemeridis Soc. Hortic. Londinensium, uec non Georgio Gardner commentatiun- 
culam ibidem (pp. 1-6) editam circa the CofFee-bug and Coffee-mildew." — ' Carp. 
Fung.' ii. p. 280. 
