196 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 



also more heterogeneous. In most Fishes the stomach is but 

 little distinguished from the intestine, nor this from the pyloric 

 appendages. In the intestinal canal itself the large intestine is 

 often hardly distinguishable from the small. The nervous sy- 

 stem of Fishes presents a brain, which predominates but little 

 over the spinal cord. 



In the Bee we meet everywhere with more heterogeneity. 

 The first coalesced pair of ganglia, although no actual brain, 

 since we can only give this name to that part of the organism 

 which forms the anterior extremity of a spinal cord, yet is far 

 more pre-eminent over the rest of the nervous system than the 

 brain of Fishes, and has more completely the signification of a 

 centre of the nervous system. I believe, therefore, that the Bee 

 is in fact more highly organized than the Fish, although upon 

 another type*. 



By type I mean the relative position of the organic elements 

 and of the organs. This relative position is the expression of 

 certain fundamental peculiarities in the direction of the vital 

 activities, e. g. of the ingestive and egestive poles. The type is 

 totally different from the grade of development, so that the 

 same type may exist in many grades of development, and con- 

 versely, the same grade of development may be attained in 

 many types. The product of the grade of development with the 

 type yields those separate larger groups of animals which have 

 been called classes. 



The confusion of grade of development with the type of 

 construction appears to me to be the origin of many failures in 

 classification ; and even in the obvious difference between these 

 relations lies evidence enough that the different animal forms do 

 not compose a single progressive series from the Monad to Man. 



* It has long been observed, that, among allied forms, those which live in 

 water, in the development of their animal, as contrasted with that of their 

 plastic functions, are below those living on land, which exhibit more marked 

 motor and physical capacities. May not the water be the cause of this? The 

 antithesis of nerve and muscle appears not to be so decidedly developed in 

 water as when there is a more active relation with the air. The muscles are 

 softer and paler, the nerves are less white and consistent. We cannot get rid 

 of the fancy that they both look as if they were infiltrated with water. When 

 in Fishes certain muscles are remarkable for their redness, as the maxillary 

 muscles of the Sturgeon, the nerves which supply them are whiter than the others. 



