HOST-INDEX OF U.S. FUNGI. 
27 
(Sphceria collapsa , S. 
ISphaerella collapsa, Che. 
Sphserella sentina ( Br .), Sacc. 
f Sphceria subbullans , S. 
ISphaerella subbullans, Che. 
Sphaeropsis malorum, B. 
Sphaeropsis malorum, B., var. foliicola, B. 8f B. 
Sporotrichum cinereum, Bh. 
Polyporus igniarius ( L .), Br. 
By the way, we hardly see the grounds for the omission, 
under the last name, of the synonym 
Fomes igniarius ( L .), Br. 
We observe another divergence from previous host-indices, 
in that the particular part of the plant is not named upon 
which the parasite is seated. It has been customary to group 
them together, as found upon, either the wood, bark, leaves, 
flowers, fruit, etc. This is not a very important omission, but 
it is a new departure. Considering the vast amount of labour 
involved in the production of such an Index, it would be most 
unfair to complain that it is not absolutely perfect. For the 
United States it is the only one, and for a general Index it is 
an important advance and aid, should any industrious Teuton 
determine to follow suit. 
Finally, this work exhibits the vast strides which the science 
of mycology has made in the States during the past quarter of 
a century, through the perseverance of a few earnest men. To 
them it is a record and a testimonial. The next work we are 
anticipating is a monograph of the Byrenomycetes. It will be 
some years before we may hope for a complete synopsis of th§ 
Fungi of the United States. 
APPLE SCAB. 
Fusicladium dendriticum. 
W e have this year received strongly developed specimens of this 
fungus on the leaves of the apple, from different parts of the 
country, and from Australia a profusion of examples. The fungus 
and its ravages are generally so well known that we may dispense 
with a description, but we will offer some observations on the 
remedies which have been proposed in the United States, where 
the pest is plentiful, as detailed in the report of the Commissioner 
of Agriculture. There remains no doubt, as we suggestedin 1873, 
that the fungus on the leaves and the fruit is practically the same. 
The fungus appears to be retarded by the heat of summer. Its 
most rapid growth takes place during moist cool weather, such as 
we have had prevailing for a long time. On the treatment of this 
pest the report in question states : “ The fungus of the apple scab 
does not penetrate into the tissues of the host, and very early in 
its development it is wholly exposed to any application which may 
be made to destroy it. It appears, however, that the vegetative 
