REVIEWS. 295 



mode of development, helps to verify or disprove this or that 

 detail of the scheme. It is from this point of view that em- 

 bryology has acquired such increased interest since the pub- 

 lication of Darwin's, Wallace's, and Haeckel's writings. 

 Breeding pigeons, to ascertain what effect the union of par- 

 ticular races will have on the form of their offspring's skull ; 

 manipulating the egg of a mollusc, so as to obtain a brood of 

 monsters, — these are surely as much experiments as Avatching 

 what will happen if you remove a dog's hemispheres. i 



It appears, therefore, that while there is an important dis- 

 tinction between a mere passive contemplation of an object 

 and a scientific observation, there is no sharp line to be drawn 

 between observation and experiment. Every experiment 

 must be followed by observation, or it is useless ; and every 

 observation in biology may be regarded as the description of a 

 ready-made experiment. Moreover, while the title " Experi- 

 mental Zoology" is unnecessary, and perhaps misleading, 

 the fact remains that zoology, in the proper sense of the 

 word, includes animal physiology, experiments, observations 

 and all ; and that, even in its restricted and conventional 

 sense, it needs, as a science of classification according to 

 genetic affinities, just the same methods as any theory of 

 secretion or innervation. 



Lastly, when these broad facts are recognised, it becomes 

 a matter of very little importance what name is given to any 

 particular investigation. So long as M. Lacaze Duthiers 

 continues to publish papers like that which follows the intro- 

 ductory chapter of this journal,^ he may be sure that biolo- 

 gists will accept them thankfully, under whatever title he 

 pleases to present them. 



P. H. Pye-Smith. 



1 In ilie kindred science of pathology almost nothing has yet been learned 

 by direct experiment. All that is known has been gained from descriptive 

 and minute anatomy, and from tlie ready-made experiments of nature ; now, 

 however, and in England of all couniries — thanks to the University of 

 London — we are likely to learn what experimental and comparative pathology 

 can teach. 



2 See the " Chronicle " for this and other papers. 



