THE DOGFISH 



the pituitary complex that was concerned with this color 

 change was shown by Lundstrom and Bard to be the 

 so-called posterior lobe, which in the dogfish probably 

 includes the portion designated in the higher vertebrates 

 as the pars intermedia. When an extract made from 

 this lobe was injected into a pale hypophysectomized 

 Mustelus a distinct general darkening of the fish oc- 

 curred within three minutes, and after an 



?*\l*!&'* 



Fig. 6. Dermal melano- 

 phores of a smooth dogfish, 

 Mustelus, showing their pig- 

 ment in extreme concentration 

 causing the fish to appear pale. 

 Lundstrom and Bard, Biol. 

 Bull., 1932, 62, pi. 4. 



Fig. 7. Dermal melano- 

 phores of a smooth dogfish, 

 Mustelus, showing their pig- 

 ment in extreme dispersion 

 causing the fish to appear dark. 

 Lundstrom and Bard, Biol. 

 Bull., 1932, 62, pi. 3. 



animal was found to be as deep in tint as were fully dark 

 normal individuals. In from five to six hours thereafter 

 the dogfish had returned to its original pale shade. 

 Tests of the effects of fractions of the posterior lobe 

 showed that an amount of extract that represented one 

 twenty-fifth of this lobe would induce a noticeable local 

 deepening of color, while that equal to one-tenth to one- 

 seventh of a lobe would excite full darkening. Com- 

 mercial preparations of the posterior pituitary lobe such 



