92 
RECENT EXPERIMENTS BY DR. MINKS. 
fungi are very soft, with thin sides, not at all gelatinous, and dis- 
solve immediately under the action of potash. 
The thallus of lichens is never viscous, while this is a very common 
property of the large species of fungi. 
The fructiferous receptacle of fungi generally differs from that of 
lichens, especially in the Pezizce ; its surface (epithecium) is bare 
in fungi ; the extremity of the paraphyses, which is often promi- 
nent and colours the disc, passes rapidly and disappears in the 
fungus. In lichens, on the other hand, the epithecium is constant; 
it is formed not only by the swelling of the prominent extremity of 
the paraphyses, but often also by a granular and persistent matter. 
Moreover, the receptacle of fungi has only a limited duration ; 
even in the Sphcerice. which lasts a long time, although not peren- 
nial, the conceptacles do not last more than a year at the outside. 
Once the Sphaeriae have developed and fructified, they have accom- 
plished their existence ; we do not see them vegetate anew. The 
suberous Polypores seem to extend their life to 14 or 15 years, 
still they really renew themselves every year, for the new fungus 
is developed on the old one, which serves it as a support, and, 
indeed, in some measure, as nourishment. Lichens, on the other 
hand, have a slow and intermittent growth. Their receptacle is 
perennial, and may last for several years, and always be in a state 
of nascent fructification. — C. Roumeguere. ( Translated from 
u Revue Mycologique,” No. 1, 1879). 
DISEASES OF PLANTS CAUSED BY PERONOS PORJE, 
MODE OF TREATMENT, &c. 
By Dr. Maxime Cornu.* 
The Peronosporce are the cause of a series of diseases which 
infest, or may infest, our crops. In order to prevent their ravages, 
one must consider first the nature and life-history of these parasites, 
secondly, that of the plant attacked, and the cultivation it requires. 
The subject is a difficult one, and requires extreme attention. 
P. gangliiformis will often be taken as an example, but most of 
the conclusions drawn from this are general, and applicable to 
other species, with some slight modifications. 
A. In order to prevent either the extension or the local production 
of the parasite. 
1°. The period of the existence of the parasite should he noticed. 
Some occur early ( 'P . Cyparissice , P. Vicice). In this case endeavour 
should be made to retard the crops until their disappearance. 
Others occur late {P. infestans). In this case the crops should be got 
in before their appearance. This last method may be adopted for 
potatoes, but not for tomatoes in our climate. 
* Translated from “ Comptes Rendus,” December, 1878, by T. Howse. 
