372 THE ZOOLOGIST. 



to which these facts are subjected, we still feel that much remains 

 unrecorded owing to the difficulties of observation. Mr. Dixon 

 forcibly expresses the opinion that migration is largely " a noc- 

 turnal drama of the air," and that " a captive balloon floated 

 above some spot where migration is notoriously prevalent, as for 

 instance at Spurn Point on the Yorkshire coast, in the Wash, on 

 the Sussex downs, or, better still, over Heligoland, fitted with a 

 powerful electric search light and various meteorological instru- 

 ments, would result in priceless information concerning the 

 annual movements of birds is absolutely certain." 



Mr. Dixon's hypothesis is that both the northern and southern 

 regions receive their migrants from the equatorial belts, but that 

 " no migratory bird normally crosses the tropics to breed or to 

 winter, in either hemisphere"; and as subsequently expressed, 

 " one set of individuals passing to the Arctic tundras, the other 

 set to Antarctic breeding grounds — from an equatorial winter 

 centre/' To make the author's proposition clear, and to accen- 

 tuate his argument, we must give another quotation : — " We 

 may conclude that the migration of birds in autumn is neither 

 due to a fall of temperature nor a failure of food, although to 

 the casual observer this invariably appears to be the case ; but 

 is initiated by a nostalgic impulse to return to certain centres 

 which are in the majority, if not in all, cases associated with that 

 gregarious instinct which in most species is only subservient to 

 reproduction, and in not a few others is equally as strongly 

 developed, as is proved by so many migratory birds breeding 

 in societies and displaying social tendencies right through the 

 summer." 



It will be thus seen that the volume is surcharged with new 

 matter, that we fain hope will meet with the candid consideration 

 of naturalists, though perhaps with small chance of general 

 acceptance among ornithologists. In fact, our author almost 

 anticipates "being ' handled without gloves' by some mud-and- 

 torpor-despising bruiser critic for my heresy." This is surely 

 unlikely, for the book is full of facts as well as suggestions, again 

 proves how the new method of enquiry has invaded ornithology, 

 and is written throughout with a felicity of language and sustained 

 advocacy which affords every weapon for the theory except con- 

 vincement, though this is all that can be expected in a general 

 way when new views are first promulgated. 



