No. 499] SUCCESSION OF SOMITES IN CHICK 471 



Patterson began his work upon it, was to throw the 

 burden of proof on those who claimed that somites do 

 arise in front of the one first formed, rather than on those 

 who held that, in their formation, they obey the laws of 

 progressive differentiation which govern the early de- 

 velopment of birds. 



Text Keferences. 

 1828. Baer, Karl Ernst von. Entwickelungsgeschichtc der Thiere. 

 1868. His. Wilhelm. Untersuchungen iibcr die Krstc Anlage des Wirbel- 

 thierleibes. 



1879. Kupffer, C, and Benecke, B. Photogramme zur Ontogonie der 

 Vogel. Verh. der Esl,Leop,Carol,Dtsch. Akad. d. Naturf., 

 Bd. 41, pp. 149-196. 



1907. Patterson. J. Thos. The Order of Appearance of the Anterior 

 Somites in the Chick. Biol. Bull, XIII, pp. 121-133. 



1898. Peebles, Florence. Some Experiments <m the Primitive Streak of 



1889. Piatt, Julia B. Studies on the Primitive Axial Segmentation of the 

 Chick. Bull. MUS. Comp. Zool., Harvard, Vol. XVII, No. 4, 

 pp. 171-179. 



