104 THE NAUTILUS. 



Each of the glands is provided with a pore. In rare cases 

 two pores have been found upon a single gland . The pores are 

 surrounded by a sphincter. When Chromodoris is violently 

 disturbed in any way, its consistent reaction is to withdraw the 

 gills and rhinophores, to erect the lateral edge of the mantle, 

 and to turn under, ventrally, the posterior part of the mantle 

 bearing the glandular organs. At the same time the glands 

 become turgid, through the contraction of their muscular in- 

 vestment, the pores being then more prominent. If the irritat- 

 ing stimulation is continued, there issues from the pores of one 

 or more of the glands a white creamy secretion, which is not 

 dissolved by sea water. It is composed maiply of globules of 

 an oily substance. The secretion is not acid, but is neutral to 

 litmus. 



When the glands are stimulated individually with induction 

 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 ventral ward 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 microchernically 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. 



