114 



FREDERICK TILXEV AXD LUTHER F. WARREN 



5. Comparative 



n/nl hixtolotji/ of the epiphyseal complex 



in tun /tliihid 



In aini)liil)i:i the pineal organ alone makes its appearance. 

 In no other form is this organ so little developed. It presents a 

 small end-vesicle which Stieda' 7 '' first recognized and described 

 as the frontal xuhctihun'oux (/land. This end-vesicle is attached 

 by means of a thread-like strand to a considerably expanded 

 proximal portion, to which latter the name of epiphysis or corpus 

 pineale has been ascribed. The pineal organ consists, there- 



Fig. GO Head of Kana temporaria showing the unpaired pineal eye, situated 

 the paired eyes, according to Stieda, 1865. 



fore, of the usual parts, namely, an end-vesicle, a stalk, and a 

 proximal portion which is particularly conspicuous in amphibia,. 

 The end-vesicle in so far as is known, is present in all forms 

 except If i/l(i arborea, the absence in this form being noted both 

 by de( Iraat', 1 " and Leydig.- :is In shape, the end-vesicle is round. 

 oval, or kidney-shaped. Stieda 17 '' and dedraaf 1 " found it solid, 

 containing a lumen only in Ijoinf>in<ilor. According to Stieda. 

 its diameters ace from .12 to .1") mm. dedraaf found these 

 diameters in l\<in<t esculenta from .\'2(\ to .14") mm., while 

 Lessona- 11 in the forms studied by him found that t lie diameter 

 was less than 1 mm. A number of observers, including Ostrou- 

 moff 2 " ('87); Lcydig^ ('91) ; Galeotti 140 ('96), and Braem" ('US), 



