418 Mr. Bowman on the Parasitical Connection 



invariably acquire a pale and sickly tint for want of the stimulus 

 of light to fix the carbon and throw oflf the oxygen. DeCandoUe 

 says, that under such circumstances they are without perspiring 

 pores. We also know, that the etiolated parts of some varieties 

 of Celery, the under surface of the leaves of Nymphaa, Hydro- 

 charis, &c. &c. are tinged with the same beautiful violet hue as 

 the flowering-stems of the Lathrcea. These striking coincidences 

 render it probable that the cadaverous appearance of our plant 

 is chiefly owing to the absence of leaves and of pores on the 

 flowering-stems, to the condition of the absorbents of the sub- 

 terranean leaves, and to its subsisting on food elaborated by a 

 foreign agent. But in what manner, and in what degree, each 

 of these causes operates and combines. Chemistry has not yet 

 discovered ; nor will she probably be ever able to draw aside 

 the impenetrable veil which checks our researches, and baffles 

 the proud philosophy of man. By the aid of the microscope 

 we can often detect the mechanical contrivances by which 

 various operations in Nature are effected ; we can explore her 

 laboratory, determine the elements, inspect the apparatus, and 

 witness the results. But we can no more explain the delicate 

 and subtle chemistry by which, in the vegetable body, the air 

 inhaled bj^ the leaves is assimilated with the juices drawn up 

 through the roots, and converted into woody fibre, and into 

 innumerable secretions, odours, and colours, than we can tell 

 how, in the animal, distinct and discordant fluids are all elabo- 

 rated from the blood, to support the various functions of life, 

 and the organs of sense and intelligence ! 



EXPLA- 



