130 



concerned in the process, occurs in the liquid state and is not solid, - - hence, a new 

 argument for the more and more prevailing opinion, that the living protoplasm is, 

 if not quite, at least partly liquid. That the juice can be precipitated with alcohol, 

 without the precipitate becoming inactive, proves nothing for the enzyme-hypothesis, 

 as in many other cases the living protoplasm is proof against the action of alcohol. 

 If it be thought desirable to use the name of protoplasm only for the mixture 

 of the living matter such as it occurs in the cell, and to connect with that term the 

 idea of a special structure, I can quite well share this view, and will allow that, in 

 this case, the decomposition of the carbonic acid is brought about by something else 

 but the protoplasm*, namely by a portion of it. To this portion, or rather, to this 

 particular constituent of the protoplasm, the name of oxybiophores or oxy-pan- 

 gens might be given, in accordance with the theory of biophores or pangenesis. With 

 what has always been understood by enzymes, the properties of the biophores do not 

 coincide but, of course, they do with those of the protoplasm itself 1 ). 



With crushed algae 1 could also perform the above experiment, but the secretion 

 of oxygen was much slighter than with the sap of the examined land-plants. 



On the other hand, algae which have not been crushed, whether enclosed in a 

 mixture of culture-gelatin and luminous bacteria, or simply in sea water rendered 

 luminous by phosphorescent bouillon, are very well fit to study the secretion of 

 oxygen in the light and its relation to the colour of the light. 



Some years hence, Prof. K a m e r 1 i n g h O n n e s , at Leiden, had the kindness 

 tr enable me to make an investigation thereabout in his laboratory. Our experiment 

 was conducted as follows. 



Between two glass-plates was enclosed fish-bouillon-gelatin diluted with sea- 

 water, and thus containing 3 pCt. Cl Na, which by a great number of phosphorescent 

 bacteria (Photobacter phospiiorescens), mixed with it, was highly luminous at suffi- 

 cient access of oxygen. In the middle of the gelatin I had placed, before the solidi- 

 fication, a broad stripe of a sea-C7/z>o. 



In the dark the gelatin quickly closes its luminosity, the glassplates rendering 

 access of air impossible. When exposed to the light, the Ulva produces oxygen 

 through the decomposition of carbonic acid, and a local spot of light appears, which 

 may be caused to come and to vanish at will as often as desired. 



This apparatus was set up in a simple camera and could be locally illumined 

 by withdrawing a slide. When the slide was closed the camera was quite dark, by 

 which the eye of the observer became sensible to the light. Prof. O n n e s himself 

 .supplied spectral colours of known refrangebility, taken from the spectrum of an 

 electric arc-light, and projected them on the Ulva in the gelatin. By me was then 

 observed what coloured lights were well, and what were not able to cause the decom- 

 position of carbonic acid. The result was the following: Only red light decomposes 

 carbonic acid, for only in it the phosphorescent bacteria emit a strong light; the 

 maximum of decomposition was found near the chief absorption-band of the chloro- 

 phyll-pigment, situated between B and C, and this maximum coincides about with C 



') This observation holds also good with regard to Buchner's alcoho!-enzyme, 

 of which the active agent consists in alcohol-biophores. 



