500 THE HISTORY OF BIOLOGY 



prepared for the rest of their lives to swear by the master's word. This 

 influence he won not through his lectures, for they were not very perfect 

 in form, but through the keen interest he showed in his pupils' work, pro- 

 vided that it followed the right direction; in the laboratory he was a friend 

 and comrade to his pupils and followed their careers in after life with never- 

 flagging interest. But he could never endure contradiction; as a controver- 

 sialist he was bitter and irreconcilable, although he invariably controlled 

 his language. At Jena he collaborated loyally with Haeckel, and the ex- 

 change of ideas that took place between them was mutual. After he removed 

 to Heidelberg, however, this co-operation ceased and even their friendship 

 cooled off, as Haeckel devoted himself to popular agitation, of which his 

 friend never approved. In his old age it was the Hegelian philosopher Kuno 

 Fischer who was in closest contact with Gegenbaur; he described the latter 

 as a deep thinker, which in its way characterizes him correctly. 



Gegenbaur's first works came into being during his visit to the Medi- 

 terranean and comprise studies of the anatomy and evolution of various 

 marine animals; in particular, medusa; and other Coelenterata, Ascidia, and 

 worms were investigated by him during this period, many of them with 

 important results. Soon, however, he went over entirely to the study of the 

 Vertebrata. One of his earliest works in this field is an essay on the evolution 

 of the egg, published in 1861; in this he shows that all eggs of the Verte- 

 brata are simple cells; hitherto it had been supposed that the egg of the 

 bird, for instance, was a multicellular organ, whereas the granules in the 

 yolk were held to be independent cells. In this connexion he strongly sup- 

 ports Max Schultze's view that the cell need not necessarily possess a mem- 

 brane, but that the plasm and the nucleus are its principal com.ponents. This 

 investigation, which of all Gegenbaur's writings is perhaps of the great- 

 est value in the field of discovery, was followed by a long series of other 

 works, wherein he applies to different organic systems in the Vertebrata the 

 comparative method which he worked out in order to confirm Darwin's the- 

 ory, and the main principle of which is to discover by means of anatomical 

 comparisons the affinity between the animal forms due to descent. His finest 

 productions on this subject, taken as models for the whole generation of 

 research students, were his comparative studies of the skeleton, which were 

 brought together in the work Untersuchungen Tur vergleichenden Anatomk der 

 Wirbeltiere. Among these studies the most notable is the essay entitled " Car- 

 pus und Tarsus," in which he compares piece by piece the bones of the hand 

 and foot in different vertebrate animals, establishes their identity, and en- 

 deavours to reconstruct the form of extremity at one time possessed by the 

 ancestors of the Vertebrata. This primal extremity he terms in a subsequent 

 treatise " archipterygium " ; he holds that it has been developed out of the 

 gill apparatus and reconstructs the modifications by which have been evolved 



