156 CONSERVATIVE ORGANS. [LECT. IV. 



blance to the tuber ; but although the new caudexes 

 of these roots bear buds, which may be correctly 

 regarded as lateral progeny, yet, these caudexes 

 are nevertheless real roots, and do not accord with 

 the definition of tubers. I shall have to notice 

 them more particularly when we examine the di- 

 rection of roots. 



As in tuberiferous plants, the tuber is formed 

 by the plant of the present year, and itself forms 

 that of the succeeding, which again forms a 

 new tuber or tubers, it becomes a subject of 

 rational inquiry to ascertain the part which the 

 real roots of the plant act, in producing these 

 results. That the plant is sustained to a cer- 

 tain degree by the absorbing powers of the real 

 roots, is obvious ; but it has not, yet, been deter- 

 mined to what extent or at what period it might 

 be deprived of the tuber and be supported solely 

 by the roots. In the early stage of its growth it is 

 altogether nourished by the tuber, the nutriment 

 passing directly from the tuber into the vessels of 

 the stem, and ascending through them to nou- 

 rish the plant. When the roots begin to absorb 

 from the soil, the fluid matters they take in 

 are probably mingled, in the leaf, with the already 

 formed nutriment brought from the tuber ; and it 

 is not unlikely that it is from the proper juice pro- 

 duced by the exposure of this mixture to the air 

 and light in the leaf, that the new tubers are 

 formed. That the new tubers, however, may be 



