1897.] Vegetable Physiology. 233 
Peronosporaceæ, except that so far as could be ascertained all the con- 
tents of the antheridium pass over into the oogonium. This is a de- 
parture from the usual course for Phytophthora, in which, according to 
de Bary (1881) and also Strasburger (Lehrbuch der Botanik, 1894) 
only a part of the contents pass over. 
_ Phytophthora nicotianæ has the omnivorous habit of P, cactorum 
C. & L. (P. omnivora de Bary), attacking species of Amaranthus and 
seedlings of Androng as well as tobacco. The habit of the conidiophores 
also resembles this species especially in the absence of the swellings 
under the conidium so characteristic of P. infestans. It differs, however, 
from P. omnivora in the size of the conidia, which are 50, 60 or 90 mic. 
mil. long by 35 or 40 mic. mil. wide in P. omnivora, and only 36 x 25 
in P. nicotianæ. The size of the conidia brings it closer to P. phaseoli 
Thaxter in which they are 35-50 x 20-25 mic. mil. in size. The biologi- 
cal identity not having been established the author decides to call the 
present species P. nicotianæ sp. nov. 
The first symptom of the disease is a wrinkling of the edge of the 
leaf accompanied by. wilting, and, if the petiole is attacked, drooping of 
the leaf. When the attack is severe the seedlings soon change to a 
dark green slimy mass, covering the surface of the bed. The appearance 
presented is as though boiling water had been thrown over the bed. 
On older seedlings and mature plants the disease appears in spots on the 
leaves, These are at first not well defined, and have a dark center with 
indefinite circumference ; later, the center dries up and becomes trans- 
lucent, or if on older leaves, brown, and a dark green border separates 
it from the healthy portions of the leaves. The disease also attacks the 
seedlings near the ground, causing damp off. Mature plants sometimes 
show the disease in this form ; but it is nearly always due to using dis- 
eased seedlings for transplanting. . 
The account of the artificial cultures is unfortunately lacking in de- 
finiteness. 
The author made cultures in various strengths of cane sugar solution, 
5,10 and 15 per cent., in prune juice, in a decoction of tobacco ashes in 
water, on sterilized potato slices, on agar-agar mixed with peptone- 
gelatine and tobacco water, and on slices of banana. All failed, except 
those in 5 per cent, sugar water and on sterilized potato. These gave 
fairly good results for a few days, but subsequently also died. The 
author does not state whether his sugar solution contained any mig 
genous matter, nor whether distilled water was used in making it, but 
leaves it to be inferred that such was not the case. 
