THE NAUTILUS. 105 



Such facts lead one to consider that the glands at the posterior 

 end of the animal are merely the expression of a specialized 

 development of the repugnatorial function which is the common 

 property of the whole dorsal and lateral integument. The ex- 

 posed location of the papillae also negatives the supposition that 

 the glands may be the primary seats for the elaboration of the 

 repugnatorial material, to be secondarily transported to other 

 regions of the animal's surface. As a matter of experimental 

 test, these nudibranchs when totally deprived of the beaded area 

 of the mantle remain unimpaired in their ability to develop a 

 protective distastefulness for fishes and invertebrates. 



The repulsive character of the contents of the glands is read- 

 ily established by controlled feeding tests in which food frag- 

 ments are smeared with the secretion. Such morsels are invar- 

 iably rejected. It remains doubtful, however, if this emulsion 

 of substances represents the only repugnatorial material pos- 

 sessed by Chromodoris. It seems possible that the oily element 

 of the secretion is particularly involved in the production of the 

 curiously penetrating odor which the nudibranch emits, and 

 that some other substance is also concerned in determining the 

 general distasteful quality. 



Incidentally, the glands cannot be implicated in any mutual 

 attraction between individuals at the time of pairing, for ani- 

 mals from which the glandular equipment has been completely 

 removed, are found to mate readily and deposit normal egg 

 masses. 



I have commented above on the suggestive appearance of pro- 

 tection evidenced by the inturning of the posterior beaded border 

 of the mantle. A closer analysis shows, however, that any pro- 

 tection which is in this way afforded to the conical glands is 

 purely incidental. For if the projecting "tail" of the nudi- 

 branch is stimulated (as with induction shocks), the beaded 

 portion of the mantle is not rolled under upon itself, but is 

 spread out so that the openings of the glands point in the gen- 

 eral direction of the irritated area. Their discharge under these 

 circumstances may occasionally be seen. I therefore believe 

 that the ventralward inflection of the gland-bearing portion of 

 the mantle is primarily a reaction having to do with the normal 



