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always followed by digestion of the catch. This is accomplished 

 by the secretion of an acid fluid containing pepsin. The digestion 

 proper resembles stomach digestion. The peptones thus obtained 

 are absorbed by the tissue of the leaf. Once inside the cells, they 

 undergo further hydrolysis and transformation. Only the protein 

 substances of the caught animals are subject to digestion. Fats 

 and polysaccharides are left untouched, thereby indicating that it 

 is the need for nitrogen compounds which has made these plants 



resort to such an unusual method of 

 nutrition. The natural dwelling places of 

 insectivorous plants, peat bogs for Drosera 

 and Dionaea, the bark of trees for epiphytic 

 Nepenthes, etc., are usually poor in nitrogen, 

 and it was Darwin who noted that sun- 

 dews, obtaining animal food, developed 

 much better and gave rise to more flowers 

 and fruit than when deprived of insects. 



We find among the higher plants also 

 true parasites, which obtain their nutritive 

 substances wholly from the host plant. Of 

 these, the most common to us are the 

 dodder (Cuscula) which at times causes 

 considerable damage to clover fields, and 

 the broom rape (Orobanche), which in places 

 makes sunflower culture almost impossible. 

 Dodder, like morning-glory and other 

 plants, entwines the stalk of the host, and 

 in addition, whenever the contact is suffi- 



Fig. 96.— Pitcher of Ncpen- . , ■ i 1 



thes suspended from the ciently strong, it sends out special suckers 

 leaf. Note amount of liquid (haustoria). Though morphologically rep- 



(F) within (after Molisch). , , . 



resenting supplementary roots, by their 

 structure they remind one more of the hyphae of fungi, which 

 penetrate into the tissues of the host, especially into its vascular 

 bundles, and suck from them the nutritive substances (Fig. 97). 

 Dodder does not possess green leaves. Having accumulated suf- 

 ficient reserves, it promptly sets to flowering and fruiting. Broom 

 rape, quite contrary to dodder, does not attach itself to the aerial 

 parts, but to the roots of the host, and in this respect bears some 

 similarity to semiparasites of the type of yellow rattle. It has no 

 green leaves and produces all its large inflorescences at the expense 



