Francis E, Lloyd —164— Carnivorous Plants 



these materials are superfluous or useless, since they live in nature 

 and not under experimental conditions. Stahl indicated the low ash 

 content of the leaves of carnivores, and advanced this additional fact 

 as an argument for the significance of carnivory. There is generally 

 also a depression of transpiration due to situation in the habitat, 

 and where transpiration is low, some other means of obtaining salts 

 is called for. The leaves of Nepenthes, when exposed to situations 

 where transpiration can act freely, do not make pitchers, and have 

 a higher ash content than those low down and exposed to higher 

 humidity, where also, as in the case of seedlings (Goebel), pitchers 

 are immediately produced following the cotyledons. Stahl thus 

 argues: the carnivory has been dominated by the idea that it is 

 an adaptation to obtain proteins; but the soils in which carnivorous 

 plants grow are notoriously poor ones, and therefore the question of 

 how the carnivorous plants obtain substances aside from nitrogen is 

 in need of investigation. This in 1900. Pfeffer had indicated 

 this problem (1877), thinking particularly of phosphorus compounds, 

 and his and Stahl's suggestions were fruitful ones.* 



In 191 2, Weyland and Schmid both entertained this idea, Wey- 

 LAND showing that there was Kttle of K and P to be found in the 

 meagre roots of Drosera, and Schmid finding these elements present 

 in the leaves of this plant after insect feeding, whereas before this 

 they were not to be found or only in meagre amounts (Ruschmann, 

 1914). Oosterhuis (1927) pushed investigation further along in this 

 direction. He asked the question whether the lack of any particular 

 mineral in the soil could be compensated for by insect feeding. He 

 summed up his experiments by saying that (i) mineral nutrients can 

 be taken up by the roots; (2) even if an abundant supply of nutrient 

 salts is present, the plants can not grow as well as if insect-fed; (3) in 

 view of the fact that in his experiments plants grown on a substrate 

 poor in salts but insect-fed prospered beyond plants grown on salt- 

 rich medium but not insect-fed, he argued that the significance of 

 insectivory Hes in the uptake of the cleavage-products of proteins 

 out of insects by the plant. The absorption of salts from the in- 

 sect is not excluded, but is not the important factor. Summarily 

 stated, in the lack of nitrogen in the soil, the plants can be supphed 

 this by insect prey, and then flourish better than when grown in 

 a substrate with Knop's solution supplying all elements. That plants fed 

 with insects have a higher nitrogen content than those grown ap seedlings 

 on turf carrying Knop's solution strengthened him in this view. 



Behre (1929), stimulated by an expression of doubt by Diels 

 (1906) as to the value of insectivory, asserted that such value had 

 not been proved, and instituted experiments of his own to test the 

 matter. He found that plants grown in distilled water but plenti- 

 fully fed with flies or meat throve very much better than those grown 

 in distilled water, or even in a v/eak Knop solution (M cone), in 

 both cases not fed. The differences noted became much more evident 

 toward the end of the second summer. He concluded that insectivory 

 is indeed of great moment to the plant. An important value, it 

 seemed to Be hre, hes in the taking up of inorganic salts, and that 



* Peyronel (1932) argues that if mycorrhizal fungi are parasitic, they should be found 

 in carnivorous plants, but he found none in Drosera or Pinguicnla. Mycorrhiza occurs 

 chiefly when soils are poor in nitrates and ammoniacal salts, but rich in organic matter. 



