EDITORIAL GLEANINGS. 531 



Me. Ernest Seton Thompson has published in the October number 

 of our American contemporary ■ The Auk ' a communication on " Directive 

 Coloration of Birds." The main thesis is that birds when sitting are pro- 

 tectively coloured ; and when flying, directively. To illustrate this point an 

 example is taken from mammals. " The common jack rabbit when squatting 

 under a sage-bush is simply a sage-grey lump without distinctive colour or 

 form. Its colour in particular is wholly protective, and it is usually accident 

 rather than sharpness of vision which betrays the creature as it squats. But 

 the moment it springs it is wholly changed. It is difficult to realize that 

 this is the same animal. It bounds away with erect ears, showing the black 

 and white markings on their back aud under side. The black nape is 

 exposed, the tail is carried straight down, exposing its black upper part 

 surrounded by a region of snowy white ; its legs and belly show clear white, 

 and everything that sees it is plainly notified that this is a jack rabbit. 

 The coyote, the fox, the wolf, the badger, &c, realize that it is useless to 

 follow ; the cottontail, the jumping rat, the fawn, the prairie dog, &c, that 

 it is needless to flee; the young jack rabbit, that this is its near relative, 

 and the next jack rabbit that this may be its mate, And thus, though 

 incidentally useful to other species at times, the sum total of all this clear 

 labelling is vastly serviceable to the jack rabbit, and saves it much pains 

 to escape from real or imaginary dangers." 



Yet another theory on the method of evolution ! Mr. Stuart Jenkins 

 has sent us a pamphlet on the " Origin of Vertebrates," reprinted from the 

 'Medical Age,' and published at Detroit, Michigan. The author com- 

 mences with an expression of sympathy with Lord Salisbury's well-known 

 utterances at the Oxford meeting of the British Association, and a belief 

 in the fact — never denied — " that Darwin has not said the last word in 

 regard to evolution." He also fortifies his proposition with the equally 

 well-known views of Huxley on non-fertility between hybrids. The new 

 theory, which is of course inevitable, is " that the divergence of the 

 vertebrates from the lower type was caused by the parasitic implantation 

 of one organism of the ganglionic type upon another, the implanted 

 organism giving rise to the cerebro-spinal nerve system and internal 

 skeleton." The brochure evidently requires more study than we have 

 been able to afford to render this proposition clear. We read that 

 " utility has cut but an insignificant part in structural evolution, which 

 has been brought about entirely by modifications of the cerebro-spinal 

 parasite due to variation of nutrition." This theory of Parasitism we 

 must own we fail to adequately understand, and therefore apologise for 

 representing it by a perhaps obscure digest. 



