No. 2.] THE HYPOPHYSIS OF AMIA CALl'.l. 59 



remarks, its early history is in most respects quite similar to 

 that in Amia. 



Dean has figured a very early and a very late stage in its 

 formation in Amia cafoa. No description is given of these 

 stages, but the generalizations made therefrom seem, in the 

 light of my researches, to be somewhat questionable, and to 

 them I shall later recur. 



Concerning the observations by Professor Minot I know 

 nothing further than the simple statement in Science, Feb. 18, 

 1898, that he had confirmed and extended the results of 

 B. Haller. As Haller's extensive observations did not em- 

 brace the Ganoids, I infer that this statement does not per- 

 tain to Minot's investigations upon Amia. 



With these facts before us it will be seen that a detailed 

 account of the development of the hypophysis in the last men- 

 tioned form will not be superfluous. 



The sections for this study were placed at my disposal by 

 Dr. Eycleshymer, and consist of series of sagittal, horizontal, 

 and transverse sections of the embryo and larva, in many suc- 

 cessive stages of development, up to and including the thirty- 

 fifth day after fertilization. All ages given in the following 

 descriptions are reckoned from the time of fertilization. 



Many examinations were made with the oil-immersion and 

 all the drawings have been made with the aid of the camera 



o 



lucida. The literature consulted, and that to which reference 

 has been made, consists for the most part of papers enumerated 

 by Kupffer 1 and Haller. 2 Since a very complete bibliography 

 is given by each of these authors it would be superfluous to 

 duplicate them in the present paper. 



DESCRIPTION OF STAGES. 



The earliest stage in the formation of the hypophysis, clearly 

 recognizable as such, is found in an embryo a few hours before 



1 Kupffer, C. von, " Die Entwicklung des Kopfes von Acipenser Sturio an 

 Medianschnitten untersucht." Miinchen uncl Leipzig. 1893. " ^' e I^eutung des 

 Hirnanhanges," Sitzungshcr. d. Gcscll.f. A/<>r/>/t. it. Phys. in Miinchcn. Jahrg. 1894. 



2 Haller, B., "Untersuclumgen iiber die Hypophyse uncl die Infunclibular- 

 organe," Morph. Jahrb. 1897. 



