120 THE ZOOLOGIST. 



The above quotation, with its formidable though necessary 

 terminology, may unintentionally give an impression that this 

 publication is of a more or less scholastic nature, an inference to 

 be repudiated once for all, as it abounds with interesting observa- 

 tions, many of which are quite original. The field naturalist 

 frequently finds an occurrence of which he is quite familiar used 

 as a philosophical conclusion by another observer in a way that 

 never appealed to his cognition. Thus, Dr. Willey, observing in 

 Ceylon the flights of Crows and Flying-foxes, describes these as 

 instances of " convergent homing," the same trees afi"ording 

 hospitality in regular alternation to day-flying birds and night- 

 flying mammals. Another conclusion, well stated, is that "the 

 basic quality underlying all animal life is the cryptic, the fear of 

 the sun. Basking in the sun is a dangerous pastime." The 

 chapter on "Mimicry and Homoplasy" is fair and candid to 

 both cautious adherents of the usual explanation of mimicry 

 and to its advanced apostles. " We may safely claim that the 

 possession by noxious animals of common iDarning coloration is as 

 much due to convergence as is the possession by harmless animals of 

 a common protective coloration ; and both these colour-schemes are 

 referable to conceivable though indefinite reactions. On the other 

 hand, the resemblances and associations betiveen palatable and 

 unpalatable insects are hard to explain on the tropism* theory, 

 unless ive suppose that they arose by ordinary convergence before 

 advantage was taken of them by natural selection.'' 



It is, however, impossible to do justice to Dr. Willey's enuncia- 

 tion of 'Convergence in Evolution' in a short notice like the 

 present one. A great number of facts and arguments are ad- 

 duced that can scarcely be appraised at their proper value 

 except by the few ; specialists will, on the contrary, be more at 

 home with the arguments which apply to their own studies. 

 This volume is again evidence that students of organic evolu- 

 tion are ceasing to believe that there is only one path through 

 the wood. 



>!: " Tropism means the tende\icy to react in a definite manner towards 

 external stimuli." 



