Chapter X —165— TtTosera. 



the lack of such salts in the natural environment is compensated for 



in this way. 



Came Oudm.\n in 1936 with further proofs. The virtue of his 

 experiments lies in the fact that his experimental plants {Drosera 

 capensis) were grown from seed, and the seedlings carefully chosen 

 for their uniformity, and in the further fact that the plants were 

 grown on a very uniform substrate of powdered peat which had pre- 

 viously been very thoroughly washed. Several sets of plants with 

 {a) distilled water, (b) nutrient solution without N, and (c) Knop's 

 solution, were set up and either not fed at aU, or fed with asparagin 

 1.5%, peptone 1.5%, gelatin 2% (against dist. water alone), gelatin 

 plus Knop (against dist. water only in the substrate), Knop solution 

 alone, and finally with insects. He found that plants grown on salt- 

 poor substrate, but fed insects, were quite normal. Plants grown 

 on N-free substrate could make use of asparagin and peptone as well 

 as the N-compounds occurring in insects. Plants well supplied with 

 nutrient salts, incl. nitrogen compounds, can grow well in the absence of 

 leaf-feeding with insects. Drosera can obtain nitrogen if this is not pres- 

 ent in the substrate, through its leaves, and this in organic form. 

 It can also take up through its leaves not only N, but other salts 

 as well. Oudman's conclusions correspond quite fully with those of 

 OosTERHUis. There can, therefore, be no sort of doubt that the 

 ability to absorb substances (mineral salts as well as N) is of sig- 

 nificance to the plant. It should be added that gelatin and glutin, 

 a derivative of gelatin, cause degeneration of the tentacles, so that 

 in time they entirely disappear. 



The presence of ascorbic acid in D. intermedia, suspected by Weber 

 (1938), was soon after demonstrated in the leaves of this plant by 

 Neubauer (1939) who claims to have found a content nearly as high as 

 that of a "well known paprika preparation", which itself contains 

 20-fold that of lemon juice. On this Weber (1940) again examined 

 the leaves of the same species after having been fed peptone powder, 

 and obtained evidence of a heightening of cell activity, accompanied by 

 an increase in vitamin-C content. This being a non-nitrogenous com- 

 pound, the significance of these results is quite problematical. 



Literature Cited: 



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difolia. Bot. Notiser 1917:145-192. 

 Ames, O., An easy method of propagating Drosera filiformis. Rhodora 1:172, 1899. 

 Arisz, W. H. & J. OuDMAN, On the influence of aggregation on the transport of asparagine 



and caffeine in the tentacles of Drosera capensis. Proc. K. Akad. Amst. 40:3-11, 1937. 

 Batalin, a., Mechanik der Bewegungen der insektenfressenden Pflanzen. Flora 60:33-39; 



54-58; 65-73; 105-111; 129-144; 145-154, 1877 {Drosera, 33-73; Diotiaea, 105-150; 



Pinguicula, 150-154). 

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tlioquinones and of the coloring matter of Drosera Whittakeri. Austral. Jour. Exp. Biol. 



Med. Sci. 12:203-212, 1934. 

 Behre, Karl, Physiologische und zytologische Untersuchungen liber Drosera. Diss. Ham- 

 burg, 1929. Planta 7:208-306, 1929. 

 Beijerinck, M. W., Beobachtungen und Betrachtungen uber Wurzelknospen und Neben- 



wurzeln. Verzamelde Geschriften van Beijerinck 2:7-121 (1886). 

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