938 
melon ‘‘are those of a plant transpiring freely, 
and insufficiently supplied with water, although 
at the same time there is an abundance of water 
in the soil.’’ This condition is brought about 
by the clogging of the vessels of the plant by 
the threads of an internal fungus parasite, thus 
checking the current of water which otherwise 
would supply the transpiration loss. The 
leaves of the plant sometimes wilt suddenly in 
large numbers, ‘‘so that a healthy-looking vine 
may lose all of its foliage in twenty-four to 
forty-eight hours.’’ 
The fungus concerned is a Nectria-like plant 
related to WNectriella and Melanospora. Its 
closest relationship is with Rabenhorst’s genus 
Cosmospora, from which it differs in its non-sep- 
tate ascospores. Dr. Smith proposes the name 
Neocosmospora for the genus. Accordingly the 
scientific name of the fungus is Neocosmospora 
vasinfecta (Atk.) Smith. Ten fine plates (one 
colored) illustrate the paper. 
THE FERTILIZATION OF Albugo Dliti. 
In the September and October numbers of the 
Botanical Gazette, Mr. F. L. Stevens publishes 
an important paper which adds to our knowl- 
edge of the fertilization of the Peronosporee. 
As is well known, these plants are non-septated, 
branching tubes, containing multitudes of mi- 
nute nuclei. The behavior of the nucleus is 
everywhere an interesting phenomenon, and it 
is especially so in these multinucleate plants. 
In ordinary plants and animals in the pro- 
cess of fertilization there is a union of two 
nuclei, 7. e., the odsphere, or egg, and the 
sperm, or male nucleus. In the plants studied, 
the odgone contains about 300 nuclei at the time 
when it is cut off from the remainder of the 
fungus thread, and these are materially in- 
creased by subsequent mitotic division. By a 
process of differentiation most of these nuclei 
come to lie outside of the oosphere, but fifty or 
so remain within it. The antheridium con- 
tains at first about thirty-five nuclei, which in- 
crease by mitotic division to four times the 
original number. On the opening of the an- 
theridial tube the male nuclei fuse with the 
female nuclei in pairs. The odsphere is, there- 
fore, to be regarded as a compound sexual 
organ. 
SCIENCE. 
[N. S. Vou. X. No. 260. 
THE OTTAWA ARBORETUM. 
THE Catalogue of the Trees and Shrubs in the 
Arboretum and Botanical Garden at the Cen- 
tral Experimental Farm, at Ottawa, Canada, 
prepared by Wm. Saunders and W. T. Macoun, 
is an interesting contribution to the subject of 
experimental forestry. It contains a list of the 
trees and shrubs, 3071 kinds, which have been 
tested at Ottawa during the past ten years. Of 
these 1434 have been found to be hardy, 361 
half hardy, 232 tender, 307 winter killed, 
while 737 have not been planted long enough to 
admit of an opinion as to their hardiness. 
Among the species reported as hardy, contrary 
to our expectations, are the following : dsculus 
glabra, and other species of the genus; Catalpa 
bungei and C. kempferi, Castanea dentata, Halesia 
tetraptera, Morus alba and M. nigra, Rhus cotin- 
cides and Ginkgo biloba. 
THE SPREAD OF FORESTS IN NORTHEASTERN 
IOWA. 
In an interesting paper on the forest trees of 
Dubuque county, Iowa, in the forthcoming 
tenth volume of the Report of the Iowa Geo- 
logical Survey, Professor Macbride first dis- 
cusses the forest conditions of the past with 
narrow belts of trees along the streams and 
protected bluffs. He then says: ‘‘On the ad- 
vent of civilization, the checking of prairie 
fires gave the forest here as elsewhere great re- 
lief. Young trees came up in every direction, 
partly from seeds, partly from so-called bench- 
grubs, old stump-like stocks which had been in 
the days of prairie fires again and again burned 
off, only to start again in shoots and suckers 
with the advent of spring; but destined so long 
as fires swept over them, never to attain tree- 
like dimensions. These bench-grubs sometimes 
were very old and possessed an extensive root 
system. This accounts in part for the rapidity 
with which the forests of Iowa began to spread 
with the arrival of civilized man. In the case 
before us the early farmers selected, of course, 
the more level country ; the steeper and poorer 
hills were left to nature and became quickly 
forested, covered with what is called second- 
growth, an assemblage of trees denser and 
darker than ever occur in nature under any 
other circumstances. In Julien and Peru town- 
