782 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
dark brown and two terminal hyaline cells, and each of the latter is 
prolonged into a stout curved acuminate hyaline bristle. 
Diseases caused by Fungi.* * * § — Prof. J. E. Humphrey gives a 
detailed account of the following diseases and the fungi which cause 
them : — 
The black knot of the plum, a disease very destructive to all kinds 
of plums and cherries, both cultivated and wild, in the United States, 
but not yet known in this country. It is caused by the attacks of 
Plowrightia vnorbosa, belonging to the Sphaeriacese. 
The cucumber-mildew, which has recently appeared in various parts 
of America and in Japan, on several species of Cucurbitaceae. It is due 
to Plasmopara cubensis, originally found in Cuba. 
The brown rot of stone-fruits, very widely spread both in Europe 
and America, due to Monilia fructigena. 
The actual cause of the disease known as “ potato scab ” the author 
regards as at present uncertain. 
Fungus-parasites on Pines.f — MM. E. Prillieux and Delacroix 
describe two fungi which are parasitic on and injurious to pine-trees, 
— Dothiorella Pitya , on the spruce-fir, and especially on seedlings ; and 
Physalosjpora abietina sp. n., belonging to the Sphaeriaceae, on Abies 
excelsa. 
Fructification of Physcia pulverulenta.J — Herr C. Maule has 
closely observed the development of the fructification of this lichen, in 
order to determine the correctness of Lindau’s hypothesis that the 
apothece has its origin in certain cells, found chiefly in the gonidial 
layer, to which he gives the term “ primordia.” Herr Maule finds the 
earliest appearance of the apothece in a cluster of cells with reddish 
contents confined to the boundary-line of the gonidial and medullary 
layers. The “ primordia,” on the other hand, are distributed through 
the entire gonidial layer ; and he regards them as cells differing from 
the remaining cells of the thallus in their chemical nature, but having 
nothing to do with the formation of the fructification. He proposes for 
them the term “ Lindau’s cells.” 
Germination of Spores in Saccharomyces.§ — Herr E. C. Hansen, 
in narrating his experiments w r ith three kinds of Saccharomyces, S. 
cerevisise, S. Ludwigii , and S. anomalus, states that the germination stages 
of all three were followed from one and the same spore. The germi- 
nation of S. cerevisise has already been noticed in this Journal (1885, 
p. 849). That of S. Ludwigii is chiefly remarkable from the fact that 
the yeast-cells are not developed directly from spores, but from a pro- 
mycele, and also from the fact that the new formations become fused 
together, giving rise to characteristic fusion-forms from which yeast- 
cells develope. When old spores germinate fusion-forms are not 
observed, but a transversely septate mycele arises. The spores of S. 
* Eighth Ann. Rep. Massachusetts Exper. Stat , 1890, pp. 200-26 (2 pis.). 
f Bull. Soc. Mycol. France, vi. (1890) pp. 98 and 113 (2 pis.). See Bot. 
Centralbl., xlvii. (1891) pp. 173 and 174. 
x Ber. Deutsch. Bot. Gesell., ix. (1891) pp. 209-13. 
§ CR. Travaux du Laborat. de Carlsberg, iii. (1891) part 1. See Centralbl. f. 
Bakteriol. u. Parasitenk., ix. (1891) pp. 663-4. 
