336 The Botanical Gazette. [July, 
necessary to protect the property of the garden from injury or loss. 
Persons who wish to m 
desire to do, and givin timely notice so that provision may be made 
j ose who have not published the 
results of original work should state their preparation for any investi- 
gation they propose to undertake. 
Two MOST IMPORTANT papers on physiological topics have recently 
been published in the Philosophical ‘Transactions of the Royal So- 
paper* the following results, which set some matters in a new light, 
and demand careful consideration: 
nder normal conditions, practically the sole pathway for CO; 
h mata 
2. in young leaves the cuticle seems to be no more permeable to 
CO, than in mature leaves. ; ‘ 
3. If the stomata be mechanically blocked an appreciable osmosis 
of CO, may take place through the cuticle provided that the tension 
of the CO, be great enough. 2 
4. The normal amount of CO, in the atmosphere is not sufficient to 
Pp ny appreciable osmosis into a leaf with its stomata blocked; 
assimilation therefore cannot continue under these conditi 
rimental optimu assimilation depends on 
the stomata even pure CO, may not quite effect optimal assimila- 
on. 
6. To this, and not to the stomata being inoperative in gaseous eX- 
change (which was Boussingault’s view), is due the fact that in con- 
centrated CO, a leaf with its stomata open assimilates less than one 
with the stomata blocked. the 
7. In bright light a fully green leaf assimilates all the CO, that it is 
forming by respiration, and none esca from it. Garreau’s vee 
stration to the contrary is only an expression of the imperfection 0 
the conditions under which it was performed. 
1]. c. 186 B: 48 
Ae a = 485-502. 1895. 
1; c. 186 B: 503-562. ae 
