928 



SCIENCE. 



[N. S. Vol. XVI. No. 41.5. 



As the amount of a gas taken up by a 

 solvent depends not only on its solubility, 

 Iiut upon its partial pressm-e, it is very 

 evident that we cannot compare the two 

 gases by admitting the same quantity of 

 both to plants under simultaneous compar- 

 ison. It is only necessary to supply the 

 dioxide in the proportion of four parts in 

 10,000; but the almost insoluble nature of 

 the monoxide makes it inevitable that from 

 two to five per cent, shall be experimented 

 with. The same question of solubility 

 makes it almost out of the question to ex- 

 periment with an aquatic plant. 



It would be of considei-able interest from 

 this point of view also to inquire whether 

 if carbon monoxide is liberated at the out- 

 set of the photosynthetic processes its com- 

 bination with other groupings can take 

 place apart from the action of chlorophyll. 

 If so the fungi should be capable of carbo- 

 hydrate construction if supplied under 

 proper conditions with the monoxide and 

 with hydrogen. The proper conditions, 

 however, might be extremely difficult to 

 establish. 



The next stage in the constructive pro- 

 cess affords still ample room for investiga- 

 tion. The presence of formaldehyde is not 

 the hypothesis of Baeyer alone, but is de- 

 manded according to Bach's views, though 

 the stages of its hypothetical construction 

 are not the same. We have therefore to 

 ask whether formaldehyde can be detected 

 in plants, and if so whether the conditions 

 under which it may exist admit of its being 

 fonsidered an up-grade product in photo- 

 synthesis. Objections to the theory of its 

 formation may be advanced, based upon its 

 undoubtedly poisonous nature. Of all the 

 jintiseptics now available to the bacteriol- 

 iigists it is perhaps the most potent, even 

 traces being fatal to the form of vegetable 

 jtrotoplasm which is found in bacteria. We 

 may argue that it must be equally dele- 

 terious in the cell containing chlorophyll 



and to the chloroplast itself, as we have ni^i 

 reason to suppose that any difference in 

 vitality exists between the protoplasm of 

 different plants. At first sight this appears 

 an almost insuperable difficulty in the way 

 of the theory. Formaldehyde has, however, 

 the properties of aldehydes in general, one 

 of which is the power of condensation or 

 polymerization. It passes with extreme 

 readiness into a much more inert form, 

 para-formaldehyde, a body in which three 

 molecules of the formaldehyde are grouped 

 together. It is therefore possible that it 

 may be prevented from exercising its 

 deleterious properties by a transformation 

 at once into this comparatively harmless 

 modification. This will slowly decompose 

 under proper conditions, giving off the free 

 aldehyde. 



PoUacci has stated that it is possible to 

 extract formaldehyde from leaves. In his 

 experiments he took such as had been ex- 

 posed to light for a very considerable period 

 and then macerated them in water. After 

 a sufficient extraction he distilled the 

 leaves, together with the water in which 

 they had been steeped. The first portions 

 of the distillate yielded reactions indica- 

 tive of the presence of formaldehyde. His 

 experiments do not enable us to say that" 

 free formaldehyde was there, for the more 

 stable para-iovm would be likely to decom- 

 pose during the distillation, so that the re- 

 actions would be explained without de- 

 manding the presence of the free aldehyde 

 in the leaves. 



But little success has attended hithertO' 

 the attempt to show that formaldehyde, in 

 the presence of chlorophyll, or preferably, 

 we may say, of chloroplasts, can give rise- 

 to carbohydrates. We have nothing more 

 .satisfactory than Bokorny's experiments, 

 in which, after failing to set up photosyn- 

 thesis in a filament of Spirogyra fed with 

 formaldehyde, he succeeded when he sup- 

 plied the alga with its compound witk 



