MANTLE-GLANDS OF CHROMODORIS. 113 



It is in fact known that injuries are suffered by the mantle- 

 fold and by other parts of Chromodoris, mainly (if not entirely) 

 through the biting of fishes (cf. Crozier, '190). The re-forma- 

 tion of the caudal veil, and with it of mantle-glands, after ampu- 

 tation, has been observed in the laboratory. The process was 

 slow, however (Crozier, '16), occupying some 4 months, and 

 was therefore unsuitable for experimental study; the tissue of 

 the mantle-fold is regenerated very slowly indeed, new glands 

 appearing before an excised region of the caudal veil is restored. 



The view here advanced involves the idea that the major por- 

 tion of the gland-contents, or the precursors of these contents, 

 are in some way carried from distant parts of the animal to the 

 site of the glands. It can be pointed out that the repugnatorial 

 substances contained in the glands are indeed present in the gen- 

 eral mantle surface of the nudibranch. Several instances were 

 noted wherein a nudibranch with a much injured caudal veil ex- 

 hibited 3 or 4 small white accumulations of secretion on the ven- 

 tral surface of the buccal veil. A detailed account Of these secre- 

 tions, with proof of their repugnatorial character and function, 

 I shall provide in another publication. 



Microscopically, each gland consists of a spherical sac, tightly 

 packed with oily globules of a special kind, and communicating 

 with the outside by means of a minute pore. In C. zebra the his- 

 tological conditions are not unlike those earlier figured (some- 

 what incompletely) by Bergh ('98) for C. juvenca. Bergh did 

 not observe the pore-like opening, which is difficult to see in 

 sectioned material, and indeed is absent save in mature glands, 

 and at this time the real nature of these structures was un- 

 known. On some other portions of the mantle fold, notably on 

 the ventral surface of the buccal veil, minute white bodies are 

 occasionally seen, which give rise to a similar secretion; these 

 bodies are never so large as the caudal glands. 



It has been remarked that each gland may perhaps undergo a 

 process of shrinkage, followed by growth to a maximum size. 

 This might explain such cases as are illustrated in Fig. 7. Ma- 

 terials ordinarily going to a particular gland might, if this gland 

 be in a phase of shrinkage, accumulate in several smaller, new 

 glands about its periphery ; subsequent re-growth of the original 



