24 



Dr. & tlic Hov. S. Giiiliam Rrado-Birks — 



111 a. cdi-pnithaifUii, tlicii. more tliaii oiio type of {ilaiid 

 is present, and one of these has l)cen sliown to excrete a 

 snhstanee almost certainly essential lor the production of the 

 animal's li;;iit. 



Tlnis upon such stimulation as results in the ordinary 

 production of li;;ht there are present on the ventral surface 

 of the hody : the contents of the white glands ; and, almost 

 certainly, always the contents of at least one other type of 

 ghr (1 ; and air, with its ordinary impurities inclndiufr water- 

 vapour. \Ve do not know enouj;)! of the chemical nature of 

 the contents of the individual <^lauds yet to speak confidently, 

 hut \sv. can at least conclude th:it in the excretion whicii 

 aecompaniis luminosity there arc generally present : (i.) the 



Y\s. 115. 



liiilargi'd \ ifw ot ^onio {jrUuiils of the sniue si'ctii)ii, X l<>0. 

 Loitering n^ in fig. lo. 11. K. B.-B. del. 



eoiiTents of the white glands ; for these we |)i'()()ose the 

 naiiu" u[' prutoliiciferiu *, (ii.) mucin, (iii.) acid. The last two 

 nuiy, or may not, he produced liy the same gland, and in 

 either ease jirofo/tiiifi rin may, or may not, contain acid 

 as well. 



\\'{; may now examine more closely, from the chemical 

 point of view, the conditions and incidence of luminosity in 

 (i. c(ir/)Op/i(i(/ns. 



* Luri/cn'ii, llio ninne in-opnsi'd hy Dubois lor tlie luniinon.<» llnid ho 

 nift witii in Ori/ti hiirlxiricn, inclii'les tlie wliole excretion of the ventral 

 snrfjiee suid jjiohjihly includes mucin mid an iicid, iipurt Irom unv sub- 

 atiince corre.sponding to our luutolucifciin. 



