296 BOTANICAL GAZETTE [OCTOBER 
in the transmission of impulses by Mimosa and other plants, 
in the Botanical Institute at Leipsic by the courtesy of Geh. 
Professor Pfeffer, to whom I am also indebted for his untiring 
attention and advice. 
A number of the tests were repeated in the Botanic Insti- 
tute at Tubingen in the present year, and I am indebted to the 
director, Professor Véchting, for the opportunity. Some of 
the tests have also been repeated in the plant houses of the 
University of Minnesota. 
Haberlandt’s conclusions as to the transmission of impulses 
by means of hydrostatic disturbances ina series of elongated 
cells (the “Schlauchzelle”) lying externally to the xylem have 
been received with general favor, and accounts for such a large 
number of the phenomena of transmission that certain of the 
experiments were arranged in such manner as to test the capacity 
of this theory for final explanation. 
In the first place, repetitions were made of the well known 
experiments in which impulses were transmitted through por- 
tions of stems and petioles which had been killed by steam 
or dry heat in such manner as to allow the dead portions to 
remain mechanically intact. In my own work this was accoml- 
plished by winding soft cloth around the portion to be killed 
and saturation with water at 90-100° C. for five minutes. In 
some instances the dead portions were allowed to desiccate 
and in others a Wrapping of tinfoil or a sheath of oiled plaster 
of Paris prevented undue loss of moisture. | 
I was able to transmit impulses from an incision or flam 
through dead portions of stems 3™ in length ; in some instances 
in which desiccation had proceeded to such an extent that the cell 
lumina of the dead portion were quite devoid of liquid contents, 
and in one instance through a portion bent at right angles by 
the weight of the leaf. 
I was able to obtain similar transmissions in the midrib of 
the multipinnate leaf of Oxalis sensitiva, which offers many % 
the features of Mimosa. 
In a few instances a reaction was obtained when incisions 
a a 
