pringshrim's researches on chlorophyll. 125 



in respiration so long as that process in light is in excess of 

 assimilation. Hypochlorin-forniation, therefore, is fully 

 proved to depend upon light. Its dependence upon the 

 presence of carbonic acid is difficult of experimental proof, 

 because, though seedlings may be cultivated in an atmosphere 

 deprived of carbonic acid, it is impossible by absorptive 

 agents to keep it free of the gas ; as in presence of oxygen, 

 which is here necessary for the development of the green 

 colour in the tissues, the time that must elapse before the 

 hypochlorin-formation can be detected is sufficient for 

 carbonic acid to accumulate within the tissues and to so great 

 an extent as to give rise to hypochlorin. 



Of very striking import is the fact that hypochlorin, like 

 chlorophyll colouring matter, is formed in gymnosperms 

 without the action of light. Colourless embryos of Pinus 

 picea, montana, maritima, Larix, have no trace of hypo- 

 ciilorin. Sachs showed that from the seeds of such plants 

 germinating in darkness, the embryos, though kept quite 

 dark, become green. This is quite unexplained. In the first 

 stages of germination, when the seedling is already green, 

 no hypochlorin is formed ; but in later stages, though still 

 in darkness, it appears in the tissues. Thus, hypochlorin 

 appears in gymnosperms grown in darkness, and, as is the 

 case in angiosperms after the chlorophyll colouring matter, 

 in most cases appearing in four to five weeks' old seedlings, 

 which have become green long before.^ There is no doubt, 

 however, that light favours hypochlorin formation. 



This condition in gymnosperms does not disallow the hypo- 

 thesis that hypochlorin is formed in assimilation. Although 

 formed in the embryo without access of light, yet in adult 

 gymnosperms as in angiosperms it is the result of light- 

 action. It resembles chlorophyll in this respect. Because 

 chlorophyll occurs in embryos of gymnosperms grown in the 

 dark, one does not suppose that light has no influence in its 

 production in other plants, and the like must beheld regarding 

 hypochlorin. Possibly in seedling-gymnosperms the hypo- 

 chlorin may arise by metastasis without direct assimilation. 

 A substance — perhaps a volatile oil-— may descend from 

 the mother-plant into the seeds, and out of it the hypo- 

 chlorin in the seedling may be formed. Whatever be the 

 first assimilation-product it is possible that it may be regene- 

 rated by metastasis from its own products, and for all proxi- 

 mate constituents of the plant the same process of regene- 



' The following Table illustrates the formation of Hypochlorin in Seedlings 

 of various ages of Pimts picea, grown in Darkness, some being exposed 



