322 INEZ WHIFFLE WILDER. 



With the final withdrawal of the blood from the gill bushes, the 

 latter lie against the lateral wall of the pharyngeal region like a 

 temporary operculum, and rapidly fuse with the epidermis 

 covering the surface over which they lie, thus effecting the 

 external closure of the gill slits (Fig. 23, b and c}. 



For some time after metamorphosis the whole region is in a 

 disorganized condition histologically, and sections show beneath 

 an external covering of the thinnest of epidermic layers, a great 

 meshwork of distended blood vessels, together with the remnants 

 of epithelial lining of gill slits, which through the agency of the 

 ever active leukocytes is rapidly disintegrating. 



The transition from larval to adult life involves in Desmog- 

 nathus no fundamental change in the nature of the food, since 

 throughout the whole life of the species the food consists mainly 

 of living animal forms. As would be expected, therefore, 

 metamorphosis necessitates no noticeable changes in the digestive 

 apparatus, as it does in the case of those amphibians in which 

 the nature of the food changes at metamorphosis from vegetable 

 to animal. 



ADULT STAGE. 



With regard to the growth and development of Desmognathus 

 subsequent to metamorphosis I can give no very exact data. 

 The many adults which I have measured range from 29 mm. to 

 104 mm. in length, the former showing, of course, unmistakable 

 evidences of recent metamorphosis. Specimens collected at 

 any one time do not show sufficient evidence of falling into dis- 

 tinct groups as to size to suggest definite yearly amounts of 

 growth, with the possible exception of the smaller sizes which, 

 in the case of those collected in the late spring, for example, fall 

 into groups averaging 33 mm., 43 mm., and 56 mm. in length, 

 the former recently metamorphosed, and the others presumably 

 adults of one and two years' growth, respectively. Since the 

 proportionate lengths of body regions of the smallest adults 

 show a much wider range of variation as well as a closer similarity 

 to the proportions of the larvae than to those of adults of 55 mm. 

 and over, it seems evident that not only is the growth during the 

 first year or two more rapid but that the change of length pro- 



