CHLOROPHYLL AND CHLOROPHYLL DEVELOPMENT 1097 



into a more stable form, which is clilorophyll. The difference between 

 the two types of plants is simply that in one case the transformation of 

 chromogen into chlorophyll requires the action of light, while in the 

 other case it can occur in the absence of light, entirely under the influence 

 of chemical agents on the live tissue." 



"In the case of plants which do green in darkness, it is not possible 

 to observe directly the presence of protochlorophyll. But in some 

 cases the presence of protochlorophyll may be observed, even in typical 

 representatives of plants that green in darkness, like the pine. We have 

 observed that after growing Larix and Thuja in darkness, and treating 

 them with alcohol, one may identify protochlorophyll as well as chloro- 

 phyll. This fact indicates that in some cases the transformation of chlo- 

 rophyllogen into chlorophyll is held up under the influence of unknown 

 causes which make it possible to discover its presence by means of its 

 derivative, protochlorophyll." 



Thus Monteverde and Lubimenko believe chlorophyllogen is one of 

 the group of unstable pigments which was found when they studied the 

 inner envelopes of the pumpkin-like plants. They point out that their 

 experiments with these plants have offered them ample opportunity to 

 study both chlorophyllogen and protochlorophyll and the complete series 

 of stages in the transformation of the chromogen into protochlorophyll or 

 chlorophyll. Their concluding statements concerning the work with 

 wheat, luffa, and pumpkin-like plants are: "The results of our investiga- 

 tions indicate with sufficient conviction that chlorophyll never arises 

 immediately out of colorless chromogen. This very important fact 

 unites, from the point of view of formation of chlorophyll, the plants 

 which are able to green in darkness with the plants not having this 

 property. At the same time it limits the role of light in the formation of 

 chlorophyll. The facts described above prove that under the influence 

 of light a new formation from a colorless substance does not occur, but 

 only a change of a previously arisen pigment. From this point of 

 view the formation of chlorophyll is not at all as simple a photochemical 

 reaction as one might have thought from the latest investigations of 

 Liro (36) and Issatschenko (29)." 



Lubimenko (38) demonstrated the presence of chlorophyllogen in 

 the leaves of etiolated plants. The two absorption bands found were 

 X7000 to 6800 A and X6500 to 6300 A. Light causes the chlorophyllogen 

 to become chlorophyll. Extraction of the living tissues with alcohol 

 led to the protochlorophyll of Monteverde, which was considered an 

 artificial transformation product. Chlorophyllogen seems to accumulate 

 in plants which become green in the absence of light. 



Lubimenko outlines the formation of chlorophyll by the following 

 theory : 



