NOTES ON SOME PROBLEMS OF ADAPTATION. 

 I. ON THE RE-FORMATION OF THE MANTLE-GLANDS OF 



CHROMODORIS. 1 



W. J. CROZIER, 

 HULL ZOOLOGICAL LABORATORY, UNIVERSITY OF CHICAGO. 



I. 



Upon the ventral surface of the mantle-fold which encircles 

 the body of nudibranchs of the genus Chromodoris there is often 

 found, at the posterior end of the fold, a set of small gland-like 

 nodules producing conical elevations of the skin (Fig. i). With 

 some species these organs may be absent ; in others they are rela- 

 tively invisible during life, becoming more conspicuous, however, 

 at the death of the animal. In Chromodoris zebra the glands dur- 

 ing life are usually quite obvious, appearing as a number of 

 white conical bodies rather evenly spaced about the margin of 

 the caudal veil. Here, also, they become more prominent at 

 death, due to increased fluid pressure in the tissue surrounding 

 each gland. A similar degree of enhanced prominence, an en- 

 largement of each conical eminence, is induced by intense stimu- 

 lation of the nudibranch's skin. The glands apparently act as 

 reservoirs of a repugnatorial integumentary secretion. When the 

 animal is strongly stimulated, the secretion may be seen to flow 

 from the terminal pores of one or more of the conical elevations 

 (Crozier, '16). I refer to these bodies as "glands," loosely; the 

 extent of their truly glandular activity is not yet decided. 



The number of glands present on the caudal veil of an indi- 

 vidual varies considerably, namely from o to 19. In connection 

 with an analysis of the ethology of C. zebra, I found it neces- 

 sary to investigate the physiology of these glands, and to study 

 their numerical variations. From this study certain inferences 

 may be derived as to the nature of the processes leading to the 



'Contribution from the Bermuda Biological Station for Research. No. 120. 



108 



