Conditions of its Production in the Plant. 329 



rounding protoplasm may in many cases be directly ob- 

 served. 



In this connexion the hypochlorin is especially worthy of 

 notice, not only because it is never wanting in the fundamental 

 substance of the chlorophyll-bodies, so far as these (as I shall 

 show immediately) have been produced in the light, but also 

 because it is apparently the only known substance which the 

 seedling of the Angiospermia is unable to form from its 

 reserve-materials without light. I have made a series of ex- 

 tended investigations on phanerogamous plants germinating in 

 the dark in order to test whether a direct influence of light 

 upon the formation of hypochlorin manifests itself. 



I reared the seedlings from seeds in the dark until their 

 reserve-materials were completely exhausted, and thus ob- 

 tained the noteworthy result that the yellow etiolated seed- 

 lings at no stage of their development furnish indications of 

 hypochlorin by the hydrochloric-acid reaction. This applies 

 to all Angiospermia without exception ; and although when 

 we have to do with traces of a body in extensive tissues the 

 demonstration of a negative result is a troublesome and tedious 

 affair, and I have therefore hitherto been able to investigate 

 only a moderate number of etiolated seedlings {Finsterkeim- 

 linge) of various species, I can nevertheless, from the con- 

 cordant results that I have obtained, assert with perfect cer- 

 tainty that not the least trace of hypochlorin occurs in the 

 seedlings so long as they are not exposed to the light. This 

 body originates in them only under the influence of light, 

 after a longer or shorter action of the light upon the tissues 

 which become green, and indeed at any age at which the 

 etiolated young plant is exposed to the light, provided it is 

 still capable of development. The rapidity of the virides- 

 cence of etiolated seedlings in the light depends, as is well 

 known, upon the temperature and the intensity of light ; and 

 therefore, if one does not wish to employ artificial illumina- 

 tion and warmth, it is not a matter of indifference in what 

 months the experiments are made. This applies also to the 

 formation of hypochlorin in them. 



I made my experiments in the summer months of July and 

 August, with an average temperature of about 20°-23° C. 

 (68°-73 0, 4 F.) in the place where they were carried on. At 

 this high temperature of the air the etiolated seedlings become 

 distinctly green in two or three hours when exposed to bright 

 daylight, and in from 6 to 8 or, at the utmost, 10 hours they 

 become quite a strong or even deep green. 



On the investigation of the green tissues with hydrochloric 



