Disease of Olive and Orange Trees. By W. G. Farlow. 117 
sidered distinct from Fumago salicina* The specimens from 
California certainly seem to strengthen Tulasne's suspicions; and 
we must confess ourselves quite unable to distinguish between 
Fumago salicina — found on willows, oaks, birches, hawthorn, 
quince, and pear — and Capnodium Citri, found on oranges, and, 
as the Cahfornian specimens show, also on olives. If it be said 
^;hat no asci have been seen by us, that is no reason why the 
fungus should be removed from Fumago salicina, which, in the 
conformation of its mycelium, its conidia, pycnidia, and stylospores, 
it most closely resembles. Evidently, in the group of fungi which 
we are considering, too much stress must not be laid on the length 
and shape of the stylospores. We see, in the specimens before us, 
how great is the variation in what is undoubtedly a single species. 
Neither is the fact of the branching of the stylospores very 
significant, as, in the present case, there are both simple and 
branching stylospores. If the reader will compare our Plate CL., 
Fig. 1, with that of Fumago salicina, by Tulasne, ' Carp. Fung.' 
plate xxxiv. figs. 14 and 20 — leaving out of sight, as far as possible, 
the difierent artistic merits of the two, — we think he will admit 
that in all essential particulars they are alike. In reality the 
resemblance is even greater than the limited size of our drawing 
would indicate. We have said that we found no asci; but 
Plate CL., Fig. 1, c, would seem to be the early stage figured by 
Tulasne, 1. c. fig. 20. The asci will probably be found in Cali- 
fornia ; and we do not doubt that they and their contained spores 
will prove to be like those of Fumago salicina. 
If we seem to the reader to have gone too minutely into the 
consideration of the systematic position of the fungus, it was for 
the purpose of bringing out more forcibly the fact that it is nothing 
new, or peculiar to California ; and that it is not even limited to 
orange, lemon, and olive trees, but, as we have seen, is found on a 
number of other trees. How does it happen, then, that a fungus 
so widely difiused should suddenly increase to such an extent as to 
injure two important crops ? We remarked, in passing, that the 
hyphse seemed to be, as it were, gummed to the stellate hairs, and 
in some cases to one another, by a sticky substance. We do not 
forget that, when any mycelium is growing on a leaf, a certain 
amount of dirt — including of course some oily matter — is sure to 
be entangled in its meshes. In the case of the present fungus, 
however, there is something more than an accidental accretion of 
such substances. The surface of the leaves and stems is in many 
places covered with a gummy deposit, presumably of insect, cer- 
* " Donee melius cognoscantur, a Fumagine salicicola supra descripta aegre 
etiam discriminautur, nisi sede sibi singulis assueta, turn Fumago Citri, Persoonio 
seu Capnodium Citri Montanio ; turn etiam Antennaria elceplnla, Montanio," &c. 
— ' Selecta Fungorum Carpologia,' pp. 283, 284. 
