TRANSACTIONS OF SECTION K. 789 



The idea of the poisonous nature of this gas may easily be subjected to experi- 

 mental examination. It would appear easy to expose a plant to an artiticial 

 atmosphere made up to different partial pressures of carbon monoxide, to expose 

 it in such atmospheres to various conditions of -warmth and illumination and to 

 note the effect produced. It would seem possible to examine a great variety of 

 plants in that way, to try both aerial and aquatic forms, and indeed to test the 

 matter exhaustively. It must be borne in mind, however, that the solubility of 

 carbon monoxide in water is extremely small, and that there may be a great 

 difficulty in getting it brought within the scope of the influence of the living 

 substance on that account. It must necessarily be in solution in the cell sap before 

 it can affect the activity of the chloroplast. Even the relations of solubility are 

 not, however, outside the range of experiment, and it may be that the slightly acid 

 cell sap has not the same peculiarities as water as a solvent for the gas. 



It is important again to take into account in such work the factor of sunlight, 

 on which the power of photosynthesis depends. Should carbon monoxide prove 

 capable of serving as a basis for the formation of carbohydrates, the question 

 would arise. Is the activity of the chlorophyll in sunlight confined to the 

 preliminary formation of carbon monoxide from the dioxide, or is the energy 

 derived from the light brought to bear upon the subsequent constructive pro- 

 cesses ? We have little or no accurate information as to the way in which the 

 «nergy is utilised after absorption by the chlorophyll. 



This opens up a very important but very difficult line of work, which brings 

 home to us the intimate dependence of vegetable physiology upon physics. The 

 absorption of energy from without, in the form of the radiant energy of the solar 

 rays, is certainly a fact, and to a certain extent we can picture to ourselves the way 

 in which it is secured. The spectrum of chlorophyll shows us a number of 

 absorption bands whose position corresponds with the position in the spectrum of 

 the places where oxygen is liberated in photosynthesis. But the transformation 

 and applications of energy in the body of the vegetable organism need much closer 

 «xamination. The intimate relationship between the different manifestations or 

 forms of energy and the ways in which they can be transformed into one another 

 have been very minutely scrutinised in recent times. What then should hinder 

 us from learning something much more definite than we at present know about 

 these transformations in the role of vegetable life ? The electrical phenomena 

 •connected with the movements of the leaves of the Venus's fly-trap {Dionaa 

 musciinila) have been examined with considerable completeness by Burden 

 Sanderson, and we have learned that the vegetable and animal organisms show 

 considerable similarities in this respect. Recently again Bose has made important 

 contributions to the subject of the electrical responses to stimulation that can be 

 observed under particular conditions. A promising beginning has thus been made, 

 but only a beginning. The electrical condition of the normal plant under different 

 conditions of rest and activity has still to be investigated. If we return to the 

 subject of photosynthesis and the work done by the chloroplast, may we not hope 

 to discover something about the transformation and utilisation of the radiant 

 energy associated somehow with this structure ? Considering the relations 

 between the manifestations of energy which we appreciate respectively as light and 

 electricity, it does not seem wildly improbable to imagine that the energy 

 absorbed as the former may lead to a possible electrolysis of carbonic acid under 

 the influence of the chloroplast, with the formation of carbon monoxide and 

 oxygen. Pfeffer has suggested that perhaps the decomposition of the gas is not 

 due to the light rays at all, and that they may exercise only a stimulating influ- 

 ence upon the chloroplast, the energy concerned being derived from heat rays 

 directly absorbed, or heat vibrations derived from the more rapidly vibrating 

 light rays. In this case is the decomposition brought about directly by the heat 

 vibrations, or have we a transmutation into some other form of energy P The 

 "whole subject seems at all events a promising subject for inquiry. 



Another problem connected with the action of chlorophyll is associated with 

 the absorption of radiant energy by the different regions of the spectrum. Bands 

 of considerable intensity are noticeable in the blue and violet, though the deepest 



