TRANSACTIONS OF SECTION K. 791 



doubtedly poisonous nature. Of all the antiseptics now available to tlie bacterio- 

 logists it is perhaps the most potent, even traces being fatal to the form of 

 vegetable protoplasm which is found in bacteria. We may argue that it 

 must be equally deleterious iu the cell containing chlorophyll and to the chloro- 

 plast itself, as we have no reason to suppose that any diti'erence 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 

 polymerisation. 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 tbat 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 tbat it is possible to extract formaldehyde from leaves. In 

 his experiments he took such as had been exposed to light for a very considerable 

 period and then macerated them in water. After a sufficient extraction he dis- 

 tilled the leaves, together with the water in which they had been steeped. The 

 first portions of the distillate yielded reactions indicative of the presence of form- 

 aldehyde. His experiments do not enable us to say that free formaldehyde was 

 there, for the more stable j:>a?-«-form would be likely to decompose during the 

 distillation, so that the reactions would be explained without demanding 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 photosynthesis in a filament of 

 Spirogyra fed with formaldehyde, he succeeded when he supplied the alga with its 

 compound with sodium-hydrogen-sulphite. Experiments on a more comprehensive 

 scale, conducted on a variety of plants of different habits, are needed before we 

 can regard the process as satisfactorily established, 



AVe have further to pursue the problem by an inquiry as to the nature of the 

 sugar first formed. Certain considerations lead to the view that it is probable 

 that a sugar of the aldose type must be accompanied in the plant by a ketose. The 

 hypothesis as stated by Baeyer, and so far accepted till quite recently, took no 

 account of the latter. The aldose grape sugar was the one always suggested, 

 and from this all others met with have been held to be constructed. The first 

 appearance of a ketose, levulose, or fruit sugar, has been associated with the 

 hydrolytic decomposition of cane sugar, itself constructed presumably from the 

 grape sugar. I fear sufficient attention has not been paid to probability or to the 

 normal course of chemical action in framing our hypotheses, for it is rather 

 difficult to see how some of the transformations somewhat dogmatically affirmed 

 can possibly take place. I may refer in passing to the statement that in the 

 digestion of fat or oil during germination part of it is converted into starch or- 

 sugar. 



But to return to the construction of sugar. The condensation of formaldehyde, 

 which can be brought about by the action of basic lead carbonate, leads to the 

 formation of several sugars, each yielding its characteristic oaazone. How i'ar 

 the condensation in the plant follows this is still uncertain. It is quite possible 

 that stages intervene between formaldehyde and sugar of any kind. It has been 

 suggested that formaldehyde in the presence of water maj' under the conditions 

 obtaining in the leaf give rise to glycolaldehyde, a body which forms sugar very 

 readily indeed. The formation of sugar directly from formaldehyde is a much 

 longer process and is attended with greater difficulty. 



I may call your attention here to the views of Brown and Morris traversing 

 the theory of the primary carbohydrate being grape sugar. In their classical 

 paper on the chemistry and physiology of foliage leaves they have adduced strong 

 evidence, based upon analyses of the sugar-content of leaves of Tropaolum ma.jus, 

 that in this plant at any rate the first sugar to be formed is cane sugar. Whether 



