184 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 



that the special details of the parts, i.e. of the intestinal or ner- 

 vous systems, resemble what is found in the higher grades ; for 

 the intestine and the nervous system themselves are not always 

 present; it needs only that the general character should be re- 

 cognised. We thus obtain principal series between which again 

 subordinate ones are found, according as in them the character 

 of one type is more or less mixed up with that of another. These 

 series again send out offshoots, and by no means always take a 

 rigidly straight course, since every series is fundamentally only a 

 number of spheres. After what has been said, it will cause no 

 astonishment if we neither make the series equally perfect, nor 

 draw them out to an equal length. It seems to us rather, that 

 there is evident reason why gaps must exist here and there 

 (pp. 738-747). 



What do we gain, however, by this view of the lower forms 

 of animals ? We ask in the name of the reader. We gain, 1 

 believe, a great deal. 



In the first place we safely base the conviction, that all the 

 forms of animals are by no means to be considered as uni- 

 serial developments from the lowest to the highest grade of per- 

 fection. Although from the Vibrio to the Butterfly intermediate 

 forms occur, though not at equal intervals, nor of equal deve- 

 lopment, which manifest in their form and life the grades of a 

 common character, yet no starfish nor shellfish can be in- 

 truded without completely destroying the fundamental concep- 

 tion of a genetic connexion. The same relations are repeated 

 in many fundamental types. In order to show at once the ap- 

 plication of our views to special investigations, we must call to 

 mind that the metamorphoses of animals in time have been com- 

 pared with the stages of development considered as isolated, or 

 the so-called metamorphosis in space. It has been concluded by 

 a bold generalization from a few r analogies, that the higher animals 

 run in the course of their development through the lower animal 

 grades, and sometimes tacitly and sometimes expressly they have 

 been supposed to take their way through all forms. We hold 

 this to be not only untrue, but also impossible. The general 

 type appears to us to be always unchanged, and we observe that 

 animals in the course of their development are more or less simi- 

 lar only to lower stages of the same type. The insect may per- 



