138 PLANTS WITH TRAPS AND PITFALLS TO ENSNARE ANIMALS. 



Rotifera, small Acarina, species of Aphis, Poduridse, &c, slip in. What it is that 

 prompts them to visit these hidden chambers is as hard to say as it is to give the 

 reason why the various species of Daphnia and Cyclops make their way into the 

 bladders of Utricularise. The most probable explanation is that the tiny creatures 

 push into the cavities in their search for food, and there meet their death. 



It has been already stated that Lathrcea is a parasite. Although we shall not 

 discuss the plant in that capacity until later on, we must point out now that the 

 main part of its nutriment is derived from the roots of deciduous arborescent 

 Angiosperms by means of special suckers. It only grows in regions where the 

 activity of trees and shrubs is interrupted by a winter of considerable duration. 

 As soon as the woody plants on whose roots individuals of Lathrcea are parasitic 

 acquire their autumn tints and shed their leaves, the suckers invariably perish. 

 When, in the following spring, the ascent of the sap begins in the wood, Lathrcea 

 sends out new roots, which fasten their suckers underground upon the tree's roots, 

 the latter being turgid with sap. The nutriment supplied in this way to Lathrcea 

 is not essentially different from that taken up by the roots of the tree or shrub in 

 question from the surrounding earth. It is composed mainly of water holding a 

 small quantity of mineral salts in solution, a mixture which has been termed 

 not unsuitably " crude sap". 



Living underground and being destitute of chlorophyll, Lathrcea has not the 

 power of converting atmospheric carbon dioxide, or crude food-sap absorbed by 

 the suckers from the tree or shrub attacked, into the various organic compounds 

 necessary for further growth. For this reason, and inasmuch as the quantity of 

 nitrogenous compounds in the fluids withdrawn from the roots is but small, every 

 additional supply of organic food, especially of nitrogenous matter, such as is 

 derived from captured animals, must be exceedingly welcome. Although the prey 

 that is caught and digested consists for the most part of minute Infusoria, this 

 addition must not by any means be undervalued. We must take into account the 

 fact that every one of the innumerable leaf-scales of an individual Lathrcea has an 

 apparatus for capture and digestion, and that this apparatus is active throughout 

 the entire year. The frost in winter does not reach so deep down in the soil as the 

 place where the plant is imbedded, so that there, even at a season when above- 

 ground everything is quiescent, the Infusoria and other little organisms continue 

 their existence and may be captured by Lathrcea. Thus, the extremely large 

 number of animals secured in the course of a year is nearly sufficient to maintain 

 the size of each individual plant. 



It is after all anything but strange that a root-parasite, destitute of chlorophyll 

 and living underground, should make use of traps for animals, besides absorbing 

 crude sap from other plants; but, on the other hand, we are naturally surprised to 

 find plants which actually extract food from the earth by means of absorption- 

 cells, also absorbing through suckers from roots in the capacity of parasites, and, 

 furthermore, preying upon animals. An instance of such a plant is afforded, 

 however, by Bartsia alpina. This remarkable organism is distributed in the 



