256 THE NOCTILUCA. 



From the point whence the viscera hang, a number 

 of vessels diverge on all sides, in the substance of the 

 integument. They narrow speedily, ramify, and con- 

 nect with each other by the branches. The distance 

 to which they can be traced, and their number, differ 

 greatly in individuals. 



I endeavoured to excite the light-producing action 

 under the microscope. For this purpose I isolated 

 two drops of water on the compressorium, the one 

 fresh, the other salt containing one or more Nocti- 

 luccB : then screwing up the glass-plate, the drops 

 were made to unite. I had expected that the contact 

 of the fresh water would kill the animal, but that a 

 spark would be evolved at the moment. None how- 

 ever appeared, though I tried the experiment repeat- 

 edly with different specimens. The contact seemed 

 to be fatal ; the gelatinous integument shrivelled and 

 puckered up, and the beautiful globe became shapeless 

 in a few seconds. I then caught two or three in a 

 glass tube, and blew them into a vessel of fresh water 

 in a dark room, but not a spark was elicited in this 

 case. 



Atig. 13. — Examining other individuals I find some 

 in which there are several of the isolated vesicles, 

 which I had supposed above to be the stomach. That 

 conjecture is doubtless erroneous. They consist of 

 yellow clear globules, with a central well-defined 

 nucleus more or less developed, of a rich reddish hue. 

 I perceive they are not strictly isolated ; each is con- 

 nected with a thick arbuscule of vessels, which diverge 

 from its vicinity in all directions, with many branches, 

 many anastomosing unions, and thickened web -like 



