FRESH IMPETUS GIVEN TO ONTOGENY. 59 



research throughout a very wide circle. We find, therefore, 

 that a large number of investigators occupied the newly 

 found field of research, and, with praiseworthy industry, 

 made a great number of distinct new facts in a short time. 

 The majority of these new embryologists are industrious 

 specialists, who have been very useful in collecting fresh 

 materials, but who have, as a rule, done but little to ad- 

 vance the general problem of the History of Germs. I can, 

 therefore, limit myself to the mention of a few names. 

 Of special importance are the investigations of Heinrich 

 Rathke, of Konigsberg (died 1861), who did much to advance 

 the History of the Evolution of Invertebrates (Crabs, In- 

 sects, Molluscs), as well as of Vertebrates (Fishes, Turtles, 

 Snakes, Crocodiles). In the subject of the Embryology of 

 Mammals, the widest conclusions are due to the careful 

 experiments of Wilhelm BischofT, of Munich. His History 

 of the Evolution of the Rabbit (1840), of the Dog (1842), of 

 the Guinea-Pig (1852), and of the Roe-Deer (1854), are as 

 yet the most important basis of study in this department. 

 Among the numerous works on the History of the Evolution 

 of Invertebrates, those of the well-known zoologist, Johannes 

 Muller, of Berlin, on Star-animals (Echinodevma), are espe- 

 cially noteworthy ; also those of Albert Kolliker, of Wiirz- 

 burg, on Cuttle-fishes {Cephalopoda); of Siebold and Huxley, 

 on Worms and Plant-animals ; of Fritz Muller (Desterro), on 

 the Crustacea ; of Weismann, on Insects, etc. The number of 

 labourers in this field has of late greatly increased, although 

 not very much of special importance has been accomplished. 

 It is evident, from the majority of recent publications on 

 Ontogeny, that their authors are not familiar enough with 

 Comparative Anatomy. The most important of the latest 



