NOCTILUCA. 17 



expansions are in these organisms protruded externally; but in the 

 interior the microscope reveals a delicate network of irregular filaments 

 that ramify in every direction, and exactly resemble in their character 

 the anastomosing threads of Gromia, represented in a preceding figure. 



(37.) In the vacuoles it is easy to perceive particles of green matter 

 or other foreign substances, which seem to afford nourishment to the 

 animal; so that these cavities doubtless perform the functions of tempo- 

 rary stomachs, although they are constantly changing their shape and 

 situation in a most remarkable manner. 



(38.) No reproductive apparatus is apparent in these little beings ; 

 yet sometimes individuals are to be seen with double bodies, and, from 

 the observations of Colonel Baddeley as recorded by Mr. Brightwell*, 

 there seems to be little doubt that the Noctiluca multiplies by spon- 

 taneous fissure. Colonel Baddeley 's researches lead him to infer that 

 this process "begins by the gradual formation of a second nucleus, 

 which after its commencement rapidly arrives at the size and appear- 

 ance of the other. A second globular substance also (termed by some 

 previous writers on the subject the mouth) is formed, in addition and 

 near to the nucleus ; and a constriction, small at first, but gradually 

 increasing, takes place, until the perfect Noctiluca3 are developed, united 

 at last by a thin band which is speedily ruptured, the whole process 

 of division not occupying more than twelve hours." The observations 

 of Dr. Buschf, and more particularly those of Mr. GosseJ, clearly de- 

 monstrate that the Noctiluca3 increase also by germs or gemmaa. 



(39.) It will surprise some of our readers to find that the N"octiluca3, 

 small as they are, feed upon Diatomaceae, and that in these microphagists 

 we have the means of supplying our cabinets with specimens of some 

 of the rarer forms. Colonel Baddeley observes that he finds that, when 

 newly captured, each Noctiluca has several Diatoms in its interior, 

 lying in the various chambers or pouches distributed through the body 

 of the animal. These Diatoms all disappear in a few days, leaving 

 nothing visible but the vacuoles or alimentary sacs filled with granular 

 particles. A very careful examination shows an orifice near the tail or 

 peduncle, the opening of which may be detected by carefully pressing it ; 

 and from this is protruded, by continuous gentle pressure, a very thin 

 hyaline sac, filling gradually with fluid and small granular particles, 

 till it attains about one-third of the size of the animal, when it bursts 

 and disappears. 



(40.) The name Noctiluca is indicative of the extraordinary faculty 

 that these little creatures possess of emitting a brilliant phospho- 

 rescent light. When a vase filled with sea- water containing them is placed 

 in a dark chamber, the slightest agitation is sufficient to excite this 



* Quarterly Journal of Microscopical Science, vol. v. p. 186. 

 t Microscopical Journal, vol. iii. p. 203. 

 | Eambles on the Devonshire Coast, p. 257. 



C 



