— 11 — 



syntax as obtained from the use of the free C0 2 of the 

 atmosphere are necessary to call forth bud production, a 

 culture of leaves was in ade in C0 2 free air in au apparatus 

 siinilar to that figured by Pfeffer. 1 At the end of three 

 weeks the leaves showed a very abundant production of 

 buds. It has long been known that plants are able to use 

 the C0 2 of respiration as material for photosyntax. Since 

 this is so, the above experiment does not prove conclusively 

 that light is necessary to effect physical or chemical changes 

 in material already present, for on account of the size of 

 the Mnium leaf, the C0 2 product from the destructive 

 metabolism would be considerable and a small amount of 

 carbohydrate food might be formed. Later experiments with 

 other species tend to show that it is the accessible supply 

 of plastic material upon which the production of buds is 

 dependent, and not upon physical or chemical changes in the 

 material already at hand. 



Experiments with leaves in colored light by the use 

 of the double-walled bell-glasses filled with the Solutions 

 of potassium bichromate, and ammoniated copper oxide, showed 

 the production of buds as well in the strongly refrangible 

 rays as in the less refrangible. The photosyntax would be 

 greatly suppressed in the leaves exposed to the blue end 

 of the spectrum, and thus this result points to a chemical 

 or physical change in material already at hand. Since 

 Klebs 2 has pointed out a difference in the relation of spore 

 protonema and leaf protonema to light in a specific case, 

 we might reasonably expect to find a difference in the leaf 

 productions from difierent species. Another point which 

 may be noted in the case of the cultures in the rays of 

 difierent refrangibility is that in both the strongly refrangible 

 and less refrangible rays, the leaves produced a much greater 

 number of rhizoids from the surface uppermost. This would 

 tend to corroborate the Statement already advanced that 



1 Pflanzenphysiologie 1 : 191. 1881. 



2 Biologisches Centralblatt 13 : 646—648. 1893. 



