126 POPULAR SCIENCE MONTHLY 



PEOFESSOE EWAET'S PENYCUIK EXPEEIMENTS.* 



r I THE views and works of Darwin have influenced in an unexpected 

 -L way the nature of the work carried on by biological investigators 

 during the latter end of this fast-dying century. To a great extent, 

 while generally holding the doctrines he held, they have forsaken his 

 methods of inquiry. 



If animals and plants have arrived at their present state by descent 

 with modification from simpler forms, it ought to be possible by careful 

 searching to trace the line of ancestry; and it is this fascinating but 

 frequently futile pursuit which has dominated the minds of many of 

 our ablest zoologists for the last thirty years. To such an extent has this 

 pedigree hunting been carried that there is scarcely a group of inverte- 

 brates from which the vertebrates have not been theoretically derived; 

 and to-day one of the ablest of our physiologists is using his great 

 powers in the attempt to trace the origin of the backboned animals from 

 a spiderlike creature, and is exercising his ingenuity in a plausible but 

 unconvincing effort to equate the organs of a king-crab with those of a 

 lamprey. This appeal to comparative anatomy and the consequent 

 neglect of living animals and their habits are no doubt partly due to 

 the influence of Huxley, Darwin's most brilliant follower and exponent. 

 He had the engineer's way of looking at the world, and his influence 

 was paramount in many schools. The trend which biology has taken 

 since Darwin's time is also partly due to a fervent belief in the recapitu- 

 lation theory, according to which an animal in developing from the 

 egg passes through phases which resemble certain stages in the past 

 history of the ancestors of the animal. For example, there is no doubt 

 that both birds and mammals are descended from some fishlike animal 

 that lived in the water and breathed by gills borne on slits in the 

 gullet, and every bird and mammal passes through a stage in which 

 these gill-slits are present, though their function is lost and they soon 

 close up and disappear. In the hope, which has been but partially 

 realized, that a knowledge of the stages through which an animal 

 passes on its path from the ovum to the adult would throw light on 

 the origin of the race, the attention of zoologists has been largely con- 

 centrated on details of embryology, and a mass of facts has already 

 been accumulated which threatens to overwhelm the worker. 



The two chief factors which play a part in the origin of species are 



* Abstract from an article in the Quarterly Review discussing Professor Ewart's ' Experi- 

 mental Investigations on Telegony,' read before the Royal Society last year, and his book, 

 'The Penyeuik Experiments,' published by Messrs. A. it P. Black. 



