370 NATURAL SCIENCE [December 



most cheering to see the attention now being paid to scientific and 

 technical education and to intellectual culture in the great commercial 

 city of Liverpool. 



The Reduction of the Teeth among Mammals 



The professors and lecturers in our Agricultural and Veterinary 

 Colleges have many opportunities of making substantial contribu- 

 tions to biology. They deal with a series of problems which the 

 student of organisms uninfluenced by artificial surroundings can 

 rarely hope to find within his range. They observe changes in the 

 structure and function of organs which they are able to correlate 

 with known factors in the process of domestication or cultivation of 

 the animals or plants they happen to study. They also have 

 facilities for embryological research among the vertebrates, far ex- 

 ceeding those obtainable under any other circumstances. We who 

 are interested in the purely theoretical questions of biology thus 

 welcome with peculiar gratification any contribution from a naturalist 

 who has taken full advantage of these favourable conditions, and 

 enlivened the dull routine of teaching with comparatively broad 

 generalisations. 



One such contribution is contained in the seventy-ninth annual 

 Programm of the Royal Wurtemberg Agricultural Academy at 

 Hohenheim, dated 1897, but received from the author, Professor 

 W. Branco, a few weeks ago. Professor Branco is the distinguished 

 palaeontologist who succeeded Quenstedt in the University of 

 Tubingen, but was unfortunately compelled by ill-health to relin- 

 quish the duties of the professorship after too brief service. Having 

 now happily recovered, he devotes his energies to the Academy of 

 Hohenheim, and his unusually wide sympathies in biology still 

 stand him in good stea"d. A short time ago he published a descrip- 

 tion of some peculiar teeth, almost human in shape, from the Upper 

 Eocene or Lower Miocene ' Bohnerz ' of Wurtemberg (Jahresh. 

 Vereins fur vaterl. Naturk. Wiirttemb., 1898, pp. 1-140, pis. i.-iii.). 

 He now follows this memoir by the present contribution, which 

 discusses the nature and origin of the reduction of the dentition 



O 



among mammals in general. 



After some preliminary considerations and a broad outline of 

 the facts, Prof. Branco applies the knowledge he has obtained in the 

 course of his professorial duties. He points out that one principal 

 cause of the reduction of the teeth is the shortening of the jaws. 

 Among domesticated animals this shortening is shown to be due to 

 at least two causes. It happens when the food requires compara- 

 tively little mastication ; animals of any particular race fed upon 

 soft food produce short-faced descendants, while others of the same 

 race continually fed upon hard food always retain longer jaws and 



