320 TWENTY-FIRST REPORT. 



ous small flowers. In the Rafllesiuceae, however, the vegetative reduction 

 goes furthest. Here we meet with a structure comparable exactly to a fungus 

 mycelium, viz. : a system of branched lilanients of short cells which force 

 their way among the tissues of the host just like the hyphae of a fungus. 

 Only on the accumulation of sufticient food do these cells at one place begin to 

 multiply to form a large mass of parenchymatous tissue, within which finally 

 appear vascular bundles and the various structures of an inunonse flowiM", 

 which in some species is a yard in diameter. Here the reduction of the vegeta- 

 tive portion is extreme and the relative importance of the reproductive portion 

 has become very great. 



What conclusions can we draw then from the foregoing as to the effect 

 of parasitism upon the parasite? Cleai-ly the simpler the structure to begin 

 with, the slighter the change, beyond the loss of chlorophyll and chloroplasts. 

 With the plants of more complicated vegetative structure two tendencies 

 appear, — a simplification and reduction of the vegetative portions of the plant 

 with a total suppression of all organs for photosynthesis (chloroplasts, leaves, 

 etc.) and an emphasixiug of (he reproductive poitioiis. Wlicn. however, the 

 former tendency is carried too far, as in the yeasts, (he reproductive portion 

 has to be reduced as well. 



