- 
“i vegesiget , depends on the presence of free oxygen. Physiologists ¥ 
ti 
_ organizations abroad, is now in a position to submit to the mem 
’ solicite 
- published in pamphlet form at Manchester in 1886, seem applicab 
. Our needs, with certain necessary modifications. In order to brin: 
» 
36 BOTANICAL GAZETTE. | February 
of assimilation? If the disruption of carbonic dioxide within the cell furnis 
oxygen directly, how can any assimilating cell suffer from want of oxygen 
Pringsheim does not admit the usual assumption italicized above. His 
opinion is that the analysis of the CO, in assimilation does not directly 
furnish oxygen, but that some other substance is formed, which, pass 
diosmotically to the surface, breaks up and liberates free oxygen. 
criticises the usual arguments based on the results of gas analysis. Wha 
bt substance is which forms oxys en at the surface he is not prepared t 
ae this be so, the breaking up of CO: and the liberation of O are tw 
rocesses, distinct both in space and time, the one occurring within th 
cell, the other at its surface. This view is supported by reference to th 
uliar liberation of oxygen exhibited Pa darkness whis both an and 
liberation is an essentially similar process, resulting from the disrupti 
of an exosmosing substance. 
He adyances other arguments to show that we are not warranted i 
concluding, as has hitherto been done, that the presence of light. chloro 
phyll and CO2 exhausts the conditions of assimilation, and that in estima 
ing its amount no other factors but light-energy and the absorption 
light by the chlorophyll have to be taken into account. Assimilation is, 
on the contrary, a physiological function of the protoplasm, and, | 
look with interest for oo 8 detailed account of his investiga 
on this important subjec 
The proposed Botanical ree Club.—The committee appointe 
by the Botanical Club of the A. A. A. S. at the New York meeting to4 
for the club in the formation a a Botanical Exchange, after considerat 
correspondence and the consultation of the rules and regulations of sim- 
of the club certain tentative propositions, on which individual opin 
ted. 
The regulations of the Botanical Exchange Club of the British 
before the botanists of the country, a synopsis of them is here pre 
arranged with reference to America instead of Great Britain 
1. The object of the club will be to facilitate the onchange al 
barium specimens of American plants, specially of rare species and 
eties.. The conditions of membership to be that each memb 
nish a parcel of specimens annually, and pay a — subscription 
