130 ILLINOIS STATE ACADEMY OF SCIENCE 



THE NASAL CAPSULE IN BUFO AMERICANS 



Frances Grassley, Knox College 

 introduction 



The literature up to the present time on the develop- 

 ment of the chondrocranium of fishes and amphibia is 

 considerable. More work, however, has been done upon 

 the latter class of vertebrates, the Urodeles and the 

 Anura especially. 



The first adequate account of the development of the 

 skull in the Anura was given by Parker in a paper pub- 

 lished in 1871. This paper, with three others published 

 in 1876, 1877, and 1881, fail to give any very detailed ac- 

 count of the process of chondrification. Born (1876) de- 

 scribes in detail the chondrification of the skull in Triton 

 cristatus, and Stohr (18711) also describes this process in 

 Triton. Terry (1906) compares the process of chondrifica- 

 tion in Amblystoma with that of Triton, finding that the 

 two agree closely. Gaupp (1893) gives a thorough-going 

 detailed study of the skull of Rana fusca. 



Most of the work on the developing chondrocranium 

 of amphibia has been made on the later stages, rather 

 than upon the early larvae. Considerable work has been 

 done upon the earlier stages of Rana, but a less amount 

 of intimate detail is available for use on the early chon- 

 drification of the toad. Later stages have been described 

 by Higgins (1920); but nothing is known of the early 

 process of chondrification in this order. Since such 

 knowledge is indispensable to a complete understanding 

 of the proper system of classification, the writer ap- 

 proached this study of the toad to determine if possible 

 what light, if any, the study of the nasal organ would 

 shed on this problem of relations drawn from previous 

 workers on classifications of the Anura. 



This work has been done in the Biological department, 

 Knox College, upon Bufo americana (the common toad) 

 which is veiy abundant in this region. The material used 

 for study was fixed in Bouin's fluid, washed, dehydrated, 

 sectioned, mounted, and stained with Delafields haema- 

 toxylin and eosin. A model was made after the Born 

 wax-plate method and then studied. Drawings of the 



