324 JOHN BEARD, 



Vertebrate animals of so novel a character, even odd and opposed to 

 what is already known of the development of the Vertebrate embryo, 

 that a cordial reception into the Acta of the science can hardly be 

 hoped for. Some consolation may perchance be mine in a remark 

 of VON Baer's to the effect that for discoveries to meet with doubts 

 on their publication may be regarded as a compliment for them. 

 And in the same passage the quotation from W. von HuiMBOLDT is 

 not less inspiriting. "Ein Buch, das gleich bei seinem Erscheinen 

 allgemeinen Beifall findet, verdiente eigentlich gar nicht gedruckt zu 

 sein, denn es enthält nur, was in den Ueberzeugungen Aller voll- 

 ständig herrschend oder wenigstens völhg vorbereitet war". 



Whatever the reception of the facts may be, they would ulti- 

 mately need their own small corner in the edifice of Vertebrate em- 

 bryology. Confirmation may be confidently looked for; indeed, such 

 is already not entirely wanting. 



It may be otherwise with the theory. My own theoretical con- 

 clusions may be offered at a later stage ; partly because theory is the 

 salt which seasons embryological research, and also in an attempt to 

 show that any and every explanation of the facts other than one 

 would seem to be not merely uncalled for but quite beside the mark. 



The history of the transient ganglion-cells in zoological literature 

 is fortunately remarkably brief; and it may therefore be given in full. 



In the present paper the appearances presented by the transient 

 nervous apparatus in a series of progressive stages of Baja hatis 

 will receive detailed description. Then an account of the general 

 development of the apparatus, its probable functions and fate will be 

 given. In Part II, which has been delayed because of the recent ac- 

 quisition of a fine series of embryos of Scyllium canicula, it is pro- 

 posed to give a brief account of the apparatus in Scyllium, Pristiurus, 

 Mustelus, Lepidosteus and some other forms, to be followed by a 

 chapter of a theoretical character on the morphological nature of the 

 apparatus. 



Historical. 



Keferences to the ganglion-cells under consideration are not 

 numerous in the literature of embryology. 



The first mention of them is apparently contained in Balfour's 



