330 Prof. Pringsheim on Hypochlorin and the 



acid it then seemed that the formation of chlorophyll ap- 

 parently long precedes that of the hypochlorin. To give an 

 idea of the course of the phenomenon, I here append a few 

 comparative data for etiolated seedlings of peas, hemp, cucum- 

 bers, and flax. 



Etiolated seedlings 8-13 days old of these species of a deep 

 yellow colour (the cotyledons of the cucumbers, as is often the 

 case with these plants in spite of their having lived in the 

 dark, having already a suspicion of green) show no trace of 

 hypochlorin in their tissues when tested with hydrochloric 

 acid. 



Etiolated seedlings 8 days old, of the same plants and the 

 same sowing, are rendered distinctly or even dark green by six 

 hours exposure to light j but their tissues show no trace of 

 hypochlorin. 



Etiolated seedlings 8 days old, of the same sowing, exposed 

 for 13-16 hours uninterruptedly to clear diffused daylight, 

 behave similarly, although already dark green. No hypo- 

 chlorin is yet to be found in their tissues. 



Etiolated seedlings 8 days old, of the same sowing, placed 

 in the light for 19-20 hours, show the first traces of hypo- 

 chlorin, although on the whole sparingly. 



Etiolated seedlings 8 days old, of the same sowing, exposed 

 for 30-31 hours to full daylight, are full of hypochlorin. 

 The plumules of the peas and hemp, the green tissue of the 

 cotyledons of the cucumbers and flax, even the young scarcely 

 coloured cells of their viridescent tissue, are now rich in hypo- 

 chlorin. 



From these investigations, therefore, it undoubtedly appears 

 that in the Angiosperms the hypochlorin originates under the 

 influence of light, and at the same time that it only becomes 

 perceptible in them at a later period than the chlorophyll- 

 colouring-matter. 



There is undeniably a relation between the two substances. 

 Does one of them proceed from the other ? I cannot here go 

 into this question, but will only point out that, from these 

 experiments, as well as from the previous demonstration of 

 its volatilization ivitlwut destruction of the colouring-matter, 

 the independent existence of the hypochlorin side by side 

 with the chlorophyll-colouring-matter in the plant may be 

 deduced with certainty. The green tissues, although they 

 already contain the colouring-matter, nevertheless, when 

 treated with hydrochloric acid, show no hypochlorin when they 

 have not been exposed to the light for a considerable time. 

 The hypochlorin therefore cannot originate only in the pre- 

 paration from the colouring-matter, but must exist in the 



