xxxviii.] CONCLUSION. 343 



keeps to a record of facts, lie is doing useful work, and 

 work that cannot be questioned ; but as soon as theories, 

 hypotheses, and deductions are introduced, an element of 

 uncertainty creeps in. The mere superficial appearances 

 presented by Nature are seldom to be depended upon. 

 They are often deceptive, and exhibit a tendency to lead 

 an observer in the wrong direction. We may refer as 

 examples to the structure of the blue mould fungi of our 

 provisions, named Eurotium repens and E. (Aspergillus) 

 glaucus, Lk. In these fungi sexual organs have been 

 described and illustrated by Professor De Bary, but 

 rejected as such by M. Ph. Van Tieghem (Bulletin de la 

 Socie'ttf Botanique de France, p. 96, 1877) ; to the supposed 

 sexual condition described and illustrated by Tulasne and 

 De Bary under Erysiphe and Peziza; both the latter 

 observations greatly need confirmation ; and to the cases 

 of erroneous interpretation mentioned elsewhere in this 

 volume. With a full knowledge of the deceptive super- 

 ficial appearances frequently presented by natural objects, 

 Mr. Charles Darwin once said that Nature "will tell 

 you a direct lie if she can " (Trans. Essex Field Club, vol. 

 iii. p. 67). 



It is not wise to become an unqualified believer or dis- 

 believer in any hypothetical views. Our knowledge of 

 Nature is at the best extremely imperfect, and the very 

 little we know of her and her ways is as nothing when 

 compared with what we do not know. 



