222 BOTANICAL GAZETTE [SEPTEMBER 
derives the entire advantage from the association is no longer tenable, Like 
wise the theory of Janse, that endotropic fungi which form mycorhizas are 
negatively chemotropic to oxygen and bear the same relation to the seed plant 
as the organism in the leguminous tubercle, is not capable of universal appli- 
cation. Such relation has been proven by Nobbe and Hiltner between Podo- 
carpus and the peronosporous fungus which forms endotropic mycorhiza with 
it, but in no other instance. 
At this stage of our investigations, thea, two distinct physiological types at 
endotropic mycorhizas are recognized: One adapted for nitrogen fixation, 
and a second for the absorption and modification, perhaps oxidation, of humes 
products by the fungus and their liberation in the tissues of the higher plant 
The greater number of examples are included under the last type. 
Ec.otropic or sheathing mycorhizas such as Monotropa perhaps appro 
imate more nearly to the latter type.3 
HE PAPER read before the Botanical Society of America, at Columbus, 
entitled “ The effect of centrifugal force upon the cell,” by Professor D. M. 
Mottier, discussed in detail the effect of centrifugal force varying from 1800 
to 1900 times that of gravity, acting for definite short periods of time, ap 
cells of certain alge, mosses, and phanerogams. In all cells operated with, : 
the movable plasmic contents, together with the inclusions, were made to 
fall into a compact mass at the end of the cell. In cells which were not 
killed outright or too badly injured, so that death resulted soon pages 
the displaced cell-contents gradually redistributed themselves in due cou 
of time. ae 
The most strikingly interesting phenomena are presented by dividing, 
cells and in the behavior of the nucleolus. In dividing cells of ae 
as Cladophora and Spirogyra, the cell-wall in process of formation “ak 
time of centrifugal action was never completed. The chloroplast pS 
and other displaced contents, on becoming redistributed, pass ieee we 
the opening in the partly formed cell wall provided this opens a 
ll : 
too small. edistributed, 
meen 
amount of chlorophyll, and a larger one partly colors 
chlorophyll. In certain cells of the plerome of Zea Mays nbrane inte 
ogams, the nucleolus was thrown out through the nuclear mem 
cytoplasm. These nucleoli never re-entered the nucleus. the dividi"g 
Other important observations were presented touching it ae 
cell and nucleus.‘ ical Ch 
3The full paper will be published in the Budletin of the Torrey ae a 
*This paper is published in the Annals of Botany for Septembet 
