THE NAUTILUS. 105 



shocks, they respond by pouring out their secretion, and the 

 same reaction occurs, on stimulation, when the portion of the 

 mantle which bears them is detached from the rest of the animal. 



Chromodoris behaves with reference to these organs in such a 

 way as to point to their importance in the animal's economy. 

 The characteristic ventralward inbending of this portion of the 

 mantle, so different from the boldness with which its lateral 

 borders are thrown into prominence when the creature is dis- 

 turbed, inevitably suggests a reflex of a protective kind. The 

 nature of the conditions which determine their discharge leads 

 one to regard the glands as repugnatorial in function. Careful 

 study of the results of feeding these mollusks to fishes and var- 

 ious invertebrates has demonstrated that these bodies cannot, 

 however, represent the sole source of offensive secretions. A 

 repulsive material, histologically and microchemically resemb- 

 ling that found in the conical glands, constitutes in fact part of 

 the secretion which proceeds from the whole integument of 

 Chromodoris, but particularly from the lateral portions of the 

 mantle. It is noteworthy that in many individuals there are 

 to be observed, especially over the region of the mouth and 

 tentacles, minute white bodies occurring on portions of the 

 ventral mantle surface remote from the conspicuous white 

 papillae. These bodies also give rise to the white secretion. 

 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 



