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 off the oxygen. DeCandolle 
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 Nymphaea, Hydro- 
charis, &c. &c. are tinged with the same beautiful violet hue as 
the flowering-stems of the Lathrea. ‘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 by 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- 
