H. G. BllONN 201 



Bronn approached the problem from quite a different stand- 

 point, from the standpoint, indeed, of Naturphilosopkie. Of 

 this the title of the book is itself sufficient proof- 

 Morpkologische Studien fiber die Gestaltungs-gesetze der 

 Naturkorper iiberhaupt mid der organischen insbesondere 

 (Leipzig and Heidelberg, I858). 1 The linking up of 

 organic with inorganic form is characteristic ; there is much 

 talk, too, in the book of Urstoffe and Urkrdfte, but underlying 

 the Naturphilosophie we can trace the same Cuvierian'treat- 

 ment of form, and see crystallise out laws of progressive 

 development that bear no small analogy with the laws 

 established by Milne-Edwards. 



According to Bronn, the ideal fundamental form of the 

 plant is an ovoid or strobiloid 2 body, for a plant reaches out 

 in two directions in search of food towards the sun and 

 towards the earth. Animals differ from plants in being 

 endowed with sensation and mobility (cf. Aristotle and 

 Cuvier), and it is this characteristic that gives them their 

 distinctive form. The main types of animal form the Amor- 

 phozoa, Actinozoa, and Hemisphenozoa are essentially 

 adaptations to particular modes of locomotion. Animals 

 either are fixed, or they move in all directions without refer- 

 ence to any definite axis, or they move in one main direction. 



The Amorphozoa or shapeless animals include many of 

 the Protozoa and sponges ; they have no typical form, and 

 most of them are sessile. The Actinozoa include such 

 animals as the Ccelentera, which are fixed, and the Echino- 

 derms, which have a central point and move indifferently 

 along any radial axis ; their form differs from the strobi- 

 loid mainly in having radiate rather than spiral symmetry. 

 The Hemisphenozoa, or bilaterally symmetrical animals, 

 include all those that habitually move forward ; they have a 

 front end and a hind end, a dorsal surface and a ventral, 

 and the mouth, sense-organs and " brain " are concentrated 



1 I have not seen the companion volume on palaeontological pro- 

 gression, Unters. ii. d. Entwickelungsgesetse der organischen Welt 

 wtihrend der Bildungszeit unserer Erdobcrfliiche, Stuttgart, 1858. 



2 "Strobiloid" because of its spiral development. The theory of 

 the spiral growth of plants played an important part in botanical 

 morphology about this time. 



