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long and ellipsoidal, while the latter would be short and globose. 
Expressed quantitively, as a result of measuring the length and width 
of 400 individuals of each species and obtaining the ratios of the length 
to the width, the conidia of P. parasitica group themselves about a 
predominating ratio of 2, while P. nicotianae are found at 1.2. Sim- 
ilarly the ratios of the conidia of all the remaining species will vary 
from 1 + to 2 +. 
8. The degree of the development of the papillum is a good char- 
acter to be employed in taxonomic work. 
9. In their germination of conidia by means of swarm spores, at least 
some of the species of Phytophthora liberate their zoospore mass into 
a bladder or vesicle, thus showing a greater relationship to Pythium 
than had been suspected. 
10. Certain of the species of Phytophthora produce chlamydospores 
either terminally or intercalarly. 
11. The measurement of the chlamydospores can be used to good 
advantage in delineating species. A sufhciently large number should 
be measured as in the case of the conidia. 
12. The relation of the antheridium to the oogonium, that is whether 
produced at the base or on a side, can be used in separating the genus 
into groups, viz. : Cactorum group and Phaseoli group. 
13. An additional group (Faberi group), analogous to the Fungi 
Imperfecti group, and embracing forms in which antheridia are ab- 
sent or where their relation to the oogonium is yet unknown, is tenta- 
tively established. 
14. In one of the several strains of P. infestans oospore-like bodies 
resembling those observed by other investigators were produced. 
Antheridia, however, were either absent, or of a very doubtful nature 
if present. 
15. As in the case of conidia and chlamydospores, a sufficiently 
large number of measurements of the oospores should be made if the 
measurements are to be used in identifying a species. 
16. On account of the variability in the size of the spore forms be- 
longing to this genus, a more ready comparison can be made by the 
use of biometrical constants than by a mass of individual measurements. 
Such biometrical constants were calculated and arranged into tables. 
By the use of these constants the identity and relationship of the 
species are further confirmed. 
17. In closely related genera, such as Pythium, Pythiacystis, 
Peronospora, Plasmopora, and Sclerospora, the identification and 
separation of species are made with difficulty. Many of the diagnostic 
