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CONTENTS. 



Page 



Dependent nutrition in seed-plants 1 



The root habits and parasitism of Krameria canescens 5 



Parasitic seed-plants of the desert 5 



Krameria canescens and some features of the Kramerias ."> 



Root-system of Krameria canescens 6 



Anatomy of the roots 8 



The haustorium 8 



Krameria and its hosts 10 



Acacia constricta 10 



Covillea tridentata 11 



Encelia farinosa 13 



Ephedra antisyphilitica 15 



Franseria dumosa 16 



Lycium andersonii 16 



Menodora scabra 17 



Parkinsonia microphylla 17 



Prosopis velutina IS 



Zizyphus parry i 1!' 



Cultures of Krameria canescens 20 



Summarization of general features of parasitism of Krameria 21 



Xeno-parasitism: the experimental induction of dependent nutrition 25 



Material and methods 25 



Total and inorganic solids 25 



Determination of acidity 26 



Cissus-Opuntia 27 



Cissus-Echinocactus 31 



Cissus-Carnegiea 34 



Cissus-Fouquieria 30 



Opuntia-Echinocactus :><> 



Autonomic movements of Opuntia .'!" 



Opuntia-Opuntia 42 



Opuntia-Fouquieria 42 



Opuntia-Carnegiea 42 



Euphorbia-Opuntia 44 



Fouquieria-Opuntia, Fouquieria-Carnegiea, and Fouquieria-Echinocactus.... 45 



Cotyledon-Opuntia 45 



Cotyledon-Carnegiea 45 



Cotyledon-Echinocactus 45 



Agave-Echinocactus 45 



Agave-Opuntia 46 



Agave-Carnegiea 47 



Tradescantia-Opuntia 48 



Miscellaneous arrangements 48 



Re'sume' of experimental results 48 



The origination of parasitism 50 



iii 



