NUTRITION. 77 



have not tallied with each other : from many experi- 

 ments upon this subject, we are inclined to believe that 

 so long as the extremities of the radicles are in an un- 

 hurt and whole condition, absorption of colouring mate- 

 rial will not take place. Hyacinths reared by us in so- 

 lutions of very pure Carmine and Indigo, showed no 

 trace of these colours in the structure of the radicles 

 under the microscope, though perhaps it may be said 

 these colours are not fine enough for absorption of them 

 to ensue. 



35. Much dispute has arisen as to whether pure 

 water alone is sufficient for a plant to grow and nou- 

 rish in, or whether it requires something else beyond : 

 experiments might be adduced in favour of both sides 

 of the question, but unfortunately in regard to many of 

 them we have still to learn what was understood and 

 employed as pure water in the experiments. Bra- 

 connot used, it is said, distilled water, but other cir- 

 cumstances render his experiments not to be relied 

 upon. For ourselves, we believe that for the mere exis- 

 tence of vegetable life, up to a limited period, distilled 

 water may serve as soil for the plant to grow in, but 

 that for the higher maturation of vegetable life, some- 

 thing is required beyond. The difficulty in this ques- 

 tion is as to the purity of the water employed, and the 

 impossibility of any matters becoming somehow or other 

 connected with it during the experiments, and this diffi- 

 culty is increased by the fact that the plant for a certain 

 period will live as it were upon itself; nevertheless, seeds 

 are said to have been produced and ripened under the 

 influence of pure water and air alone. 



36. Water in all cases is taken in by plants in much 

 larger proportion than anything else ; but whether this 

 water becomes merely fixed and remains undecomposed 

 within the plant, or whether it is decomposed and its 

 elements enter into combinations anew, is at present 

 doubtful ; most likely both circumstances take place. 



37. Whatever else may be useful for the proper de- 

 velopment of a particular individual, carbonic acid is most 



H 3 



