No. 4!);5J 



THE PHENOGAMO US PARASITES 



27 



obtain ; but the plantlet of Cuscuta, after its germination 

 upon the ground seems, by the movements of its free end, 

 to start out in search of opportunities. It adjusts its 

 mode of life to prevailing conditions by delaying its own 

 germination about a month later than that of its prospec- 

 tive victims of annual growth, and it is not discouraged 

 by failure of its first effort to find a host. In that case it 

 falls down upon the ground, shriveled and apparently 

 dying, but if soon, or even within a few weeks, some be- 

 lated normal plantlet should spring up near it, or some 

 growing branch should droop and touch it, the victim is 

 quickly seized upon by the apparently dying plantlet. 

 Such tenacity of life and apparently dominant purpose in 

 a slender, organless mass of vegetable cells is no less than 

 marvelous. 



Because the plantlet of Cuscuta develops no root or 

 rootlets it evidently possesses no real representation of 

 the epitropic portion of a normal plantlet, or at best, not 

 more than a moiety of it which lies immediately subjacent 

 to the tropaxis. The rapid upward growth of the fili- 

 form plantlet indicates that at least a considerable part 

 of the apotropic portion is therein represented. More- 

 over, because it has no cotyledons or plumule it follows 

 that the entire plantlet of Cuscuta represents only the 

 stem of the normal plantlet, or that portion of it which 

 comes between the cotyledons and the uppermost root- 

 lets. The accompanving diagram. Fig. 6, illustrates the 

 foregoing statement. 



The upper end of B 7 Fig. 6, not reaching above the 

 upper dotted line, indicates that the plantlet of Cuscuta 

 possesses no representative of either cotyledons or plum- 

 ule. Its downward extension a little below the lower 

 dotted line similarly indicates the fact that its lower end 

 enters the soil a little way, but that it does not represent 

 enough of the epitropic portion of the normal plant to 

 give origin to a root, or any rootlets. This comparison 

 shows that the whole plantlet of Cuscuta represents 

 only the stem of the plantlet of Convolvulus. 



The descriptions which have been given in the preced- 



