324 STUDIES IN LIFE AND SENSE. 



exterminate, these insect races. The parasitic habit is one which is 

 thus by no means confined to the animal kingdom, and it is further 

 illustrated in certain plants of by no means the lowliest grade. The 

 mistletoe, for instance, is a true parasite, since, sending its sucker- 

 like roots into the substance of the oak or apple to which it has 

 attached itself, it absorbs thereby the nutrient juices of its " host." 

 By aid of its own green leaves, however, the mistletoe can elaborate 

 a little food for itself, but its parasitic habits evidently supply it with 

 the largest share of its nutritive material. Even more typical as a 

 parasite is the Cuscuta, or dodder, which literally strangles flax, 

 clover, the hop, and many other plants. The dodder begins its 

 existence in a perfectly regular and normal fashion by germinating in 

 the ground. But sooner or later the parasitic habit comes to the 

 front. Above ground, the sucking roots are developed wherever the 

 dodder comes in contact with its victim ; and finally leaving the 

 ground, this malignant growth fastens itself entirely upon the " host," 

 and ultimately kills it by the strength and intricacy of its growth. 

 There appears to be developed in the case of these parasites, as 

 distinctive a series of habits as the animal world can show. In 

 respect of the so-called " instincts " which the parasitic animal is 

 believed to possess, it seems legitimate to claim for the plant at least 

 an equal, if not more elaborate, development of a guiding and 

 directing impulse towards a peculiar way of life. This latter 

 contention becomes the more reasonable when we reflect that the 

 assumption of the parasitic life has been attended in the case of 

 the plant with a far more sweeping alteration of original habit and 

 dietary than is usually the case with the animal which becomes a 

 lodger or boarder on a neighbour form. 



In respect of the choice of food, the inner life of plants discloses 

 many curious examples of the " selective " habit already alluded to ; 

 whereby the plant appears to exhibit veritable "tastes," as capri- 

 cious and apparently as undeterminable as those of higher life. 

 The " bill of fare " of the ordinary plant naturally includes those 

 elements which constitute, and which therefore go to make, the living 

 protoplasm, on the presence of which the vitality of the animal and 

 plant alike depends. Thus it may be said that all plants absorb 

 carbon, hydrogen, oxygen, nitrogen, and sulphur, and to these 

 essential elements must be added a further instalment of " chemical 

 food," in which iron plays an important part. Now, in this state- 

 ment of plant-dietary, there is nothing more remarkable than is 

 included in the nutrition of the animal. But the animal is usually 

 credited with its likes and dislikes, and is believed frequently to 

 exhibit a preference for a special diet, or for one article of diet over 

 another. Such a feature constitutes a perfectly normal phase of the 

 highest existences, but it may prove somewhat remarkable if we 



