ZOOLOG Y AND BOTANY, MICROSCOPY, ETC. 
665 
in 10,000,000 of water will prevent the germination or the formation 
of the spores of Peronospora viticola. In most cases the toxic property 
of the salt is its power of withdrawing water from the organism. 
Pythium and Saprolegnia.* * * § — Mr. T. W. Galloway finds that the 
fungus which causes the disease known as “damping off” in cultivated 
plants is Pythium Be Baryanum. It invariably attacks the roots first of 
all. It produces “ monosporous ” oogones, antherids, and zoosporanges 
within the tissue of the root and stem, and the hyphse sometimes extend 
to the leaves. 
In Saprolegnia monoica the author was unable to confirm the state- 
ment of Hartogf that the nuclei unite in pairs to form the so-called 
vacuoles. The mode of formation of the resting zoosporanges is de- 
scribed. 
Kryptosporium leptostromiforme.J — This name was given by Ktihn 
to an ascomycetous fungus found on lupins which had formed the food 
of sheep attacked by lupinose. Dr. M. Fischer has now traced out the 
life-history of this fungus on Lupinus luteus and angustifolius var. leuco- 
spermus. The only reproductive organs found were pycnids and pycno- 
spores, the fructification differing somewhat in size and other particulars, 
according as the fungus carried on a parasitic or saprophytic existence 
on the lupin stem. No formation of asci was observed ; this appears to 
take place very rarely, and possibly on a different host-plant. 
Structure and Biology of Lichens.§ — Dr. A. Minx propounds a 
modification of Schwendener’s view of the dual nature of lichens. The 
relation of the endophytic structures (gonids) to the lichen-tissue in 
which they are imbedded is not one of parasitism, but of what he terms 
syntrophism. The relationship of the former to the latter is rather that 
of a lodger ( Miether ) ; they do not live at the expense of the host, but 
rather dwell there for their own convenience, paying a tax to the host. 
The matrix is the true lichen, and many lichens have no such lodgers. 
A list of 133 lichens is given which are true “ syntrophs,” .arranged 
under the five tribes: — Parmeliacei, Calyciacei, Gyalectacei, Graphi- 
dacei, and Yerrucariacei, by far the greater number belonging to the 
Calyciacei. 
That the lichen does not consist necessarily of two distinct organisms 
is confirmed by the fact that the gonids are frequently found not only in 
the thallus but also in the apotheces. Another fact which supports the 
same view is that the same host will frequently entertain two lodgers 
belonging to different species. According as lichens carry on their 
existence with or without these lodgers, the author places them respec- 
tively under the head of “ autotrophic ” or “ heterotrophic ” lichens. The 
degree of influence of the lodger on the life of the host varies greatly, 
and often increases as time goes on ; that the cortical layer can be 
completely thrown off is strong evidence against the theory of 
parasitism. There are cases, on the other hand, in which the syntrophy 
appears to be entirely without effect on the host. 
* Trans. Massachusetts Hort. Soc., 1891, 10 pp. and 2 pis. 
t Cf. this Journal, 1887, p. 444. 
j Bot. Centralbl., liv. (1893) pp. 289-92. 
§ Abhandl. Zool.-bot. Gesell. Wien, xlii. (1893) pp. 377-505. 
