88 ON THE MORPHOLOGICAL CONSTITUTION OF 



VI. 



ON THE MOEPHOLOGICAL CONSTITUTION OF THE 

 SKELETON OF THE VEETEBEATE HEAD. 



IN an abstract which professes to give only the general 

 results of my own investigations, I cannot enter into such 

 critico-historical details as would be necessary were the 

 corresponding or opposite results obtained by other inquirers 

 to be in every instance brought forward. I am therefore 

 obliged at present to state, in a somewhat dogmatic form, 

 the results which I conceive I have obtained, and the views 

 I have been induced to take of a subject in itself extensive 

 and difficult, and one to which so many distinguished anato- 

 mists have devoted themselves. 



Nature of the Subject. The framework of the vertebrate 

 head is a syssclerotome that is, a group of sclerotomes 

 variously modified, and more or less connected, so as to form 

 a distinct whole. The points to be determined are the number 

 and modifications of the sclerotomes in the various forms of 

 vertebrate head. There are, however, some preliminary 

 questions which must be briefly examined. 



The Source and Mode of Origin of the Sclerome in the Ver- 

 tebrate Embryo. The knowledge we at present possess of the 

 source and mode of origin of the vertebrate sclerome is the 

 result of the successive researches more particularly of Pander, 

 Von Baer, Bathke, Eeichert, and Eemak, on the development 

 of the blastoderma. 



Von Baer, while he adopted the doctrine of Pander re- 



