149 
shown that the macerated vegetable fragments in the pebbles of Grand Croix ex¬ 
hibited the same progressive demolition of cell wall which is observed in modern 
cases. Yan Tieghem even believes he has seen his Bacillus Amylobacter in a silici- 
fied state.”— Erwin F. Smith. 
Vial a, Pierre. Monographie du Pourridie des Vignes et des Arbres 
fruitiers. Montpellier, 1891, iip. 121, pi. 7. 
This monograph constitutes a thesis presented to the Paris Faculty 
of Sciences by Mons. Pierre Yiala for a doctor’s degree. It comprises 
the results of eight years work, and shows important additions to the 
status of the subject as recorded in the article on Pourridie in u Mala¬ 
dies de la VigneP 
The thesis is divided into three parts. The first is historical, and 
treats briefly the relation of Agaricus melleus 7 Vibrissea hypogcea , Fibril- 
laria and Dematophora to Pourridie. The second part is confined to 
the last of these, which the author considers the principle cause of Pour¬ 
ridie. Dematophora necatrix is a species chosen for investigation, be¬ 
cause, with the exception of a few sandy places, this is the only species 
of Dematophora found on vines attacked by Pourridie. 
The parasitic and saprophytic nature of the fungus is fully discussed. 
The former has been fully proven by experiments, but is exhibited only 
by certain forms of the mycelium, the fruit being never produced until 
the host is killed. 
Five forms of mycelium are distinguished—a white flocculent myce¬ 
lium, a brown mycelium, root-like cords, Rhizomorpha fragilis , var. sub¬ 
terranean Rhizomorpha f ragilis^ var. subcorticalis , and an internal myce¬ 
lium. The Rhizomorpha forms agree externally with those bearing the 
same name, but belonging to Agaricus melleus , but the specific differ¬ 
ences are carefully pointed out. 
The fruiting forms are as numerous as those of the mycelium; they 
are clilamydospores, sclerotia, conidia, pycnidia, and perithecia. The 
two latter forms are here described for the first time, and, judgingfrom 
what is known of other fungi, they complete the life history of the par¬ 
asite. The development of these hitherto unknown forms was obtained 
by a special variation of the conditions under which the artificial cul¬ 
tures were made. Under the most favorable circumstances the pyc¬ 
nidia require from one year to a year and a half from the sowing of the 
spores to arrive at maturity; and the perithecia two years and a half. 
The author has made many valuable experiments to ascertain the 
vitality of the fungus, the proper conditions for its development, and 
its resistance to fungicides. These are of especial economic importance. 
Much space is given to a detailed morphological description of all the 
forms of the fungus, especially of the mycelium. 
A description of Dematophora glomerata is also included in the second 
part of the thesis. The mycelium, sclerotia, pycnidia, and conidio- 
phores are described. The third part includes descriptions of the fol¬ 
lowing forms which are often confused with Pourridie. Fibrillaria 
