1878.] Botany. : 693 
of all sap-conducting plants, and it attributes an important role to 
the elasticity of the cells. “When the surface-cells of a plant, 
ration, they are somewhat compressed by the air-pressure. Like 
elastic bladders, however, they tend to take their original form. 
This of course is only possible by their drawing in either air or 
water from without. Since, however, moist membranes are little 
penetrable by air, the cells draw from cells farther in a portion of 
their liquid contents. These again borrow from their neighbors 
urther down, which contain more water, and so on, either to the 
extreme root-cells or to those parts of the stem which are sup- 
plied with water from below through root-pressure.” 
To illustrate the action, M. Bohm constructed an artificial cell- 
chain. A funnel closed by a bladder represented the evaporating 
leaf; to it were connected below several glass tubes about two 
ctm. wide, closed at one end witha bladder, and joined together 
in series by means of thick walled caoutchouc tubing. In conse- 
quence of the evaporation, the membrane which closes the funnel 
mouth is bent inwards, and when it has reached a certain tension, 
water is sucked into the funnel out of the next lower cell, which 
covers its loss in like manner. Manometers, connected with cer- 
tain cells of the apparatus, indicate the amount of suction at dif- 
ferent heights. To avoid fouling of the membranes, ties acid 
was mixed with the distilled water in the cells. Since bladder 
membranes, with a not very great height of liquid para over 
them, admit passage of water by filtration, these artificial cell- 
chains (it is pointed out), must act much more imperfectly than 
the sap-conducting cells placed over one another in living plants, 
which cells, by reason of their narrow aperture, retain their liquid 
column by capillary attraction. 
It is shown that this theory is in harmony with sundry phe- 
nomena which are contradictory of the imbibition theory. 
Austin’s Muscı ApPALACHIANI.—Supplement I to Musei exsic- 
lected mostly in the eastern part of North America, by Col. F 
Austin, will interest botanists. The author proposes to publish 
additional supplements to both the Musci and Hepatice which 
have been issued, to comprise one hundred sets of from ten to 
fifty specimens each. The specimen illustrating the first supple- 
ment are to be had for $6 a set. 
Boranicat News.—Trimen’s ¥ournal of Botany for July con- 
tains a paper on the structure and affinities of Characee, W. 
Bennett. A summary is given of Dr. Kienitz-Gerloff’s exhaus- 
tive study of the development of the capsule of Phascum cuspida- 
tum. The Botanischer Zeitung contains papers by H. Hoffmann 
n experiments in culture, and by J. Sachs “on the history ofthe 
mechanical theory of growth of organic cells.”—The Annales des cee 
