THE FLAGELLATA. 91 



Stein ' has observed a division of the " nucleus " to take place, 

 whereby it becomes converted into separate masses, some of 

 which acquire an ovate or fusiform shape, surrounding them- 

 selves with a dense coat, while others become thin-walled 

 sacs, full of minute granules, each of which is provided with 

 a single cilium. The ultimate fate of these bodies has not 

 been traced. 



A careful study of the singular genus Noctiluca led me, 

 in 1855, to assign it a place among the Infusoria, and recent 

 investigations have conclusively proved that it is one of the 

 Flagellata. 



The spheroidal body of Nbctiluca miliaris (Fig. 8) is 

 about one-eightieth of an inch in diameter, and, like a peach, 

 presents a meridional groove, at one end of which the mouth 

 is situated. A long and slender, transversely striated ten- 

 tacle overhang's the mouth, on one side of which a hard- 

 toothed ridge projects. Close to one end of this is a vibratile 

 cilium. A funnel-shaped depression leads into a central 

 mass of protoplasm, connected by fine radiating bands with 

 a layer of the same substance which lines the cuticular enve- 

 lope of the body. There is no contractile vacuole, but an 

 oval endoplast lies in the central protoplasm. Bodies which 

 are ingested are lodged in vacuoles of the latter until they 

 are digested. 



According to the observations of Cienkowskv, 2 if a Noc- 

 tiluca be injured, the body bursts and collapses, but the pro- 

 toplasmic and other contents, together with the tentacle, form 

 an irregular mass, the periphery of which eventually becomes 

 vacuolated, enlarges, and secretes a new investment. But 

 even a small portion of the protoplasm of a mutilated Nbcti- 

 luca is able to become a perfect animal. Under some condi- 

 tions, the tentacle of a Nbctiluca may be retracted into the 

 body, and, at all times of the year, spheroidal Noctiluca}, 

 devoid of flagellum, tooth, or meridional groove, but other- 

 wise normal, are to be found. These last are probably to be 

 regarded as encysted forms. Multiplication may take place 

 in at least two ways. Fission may occur in the spheroidal 

 forms, as well as in those possessed of a tentacle ; it is in- 

 augurated by the enlargement, constriction, and division, of 

 the endoplast. This process takes place more especially in 

 the latter part of the year. 



i lt Oiganisnras der Infusionstliiere," ii., 5fi. 



2 "Ueber Noctiluca miliaris." (Sckulze's " Archiv fur mikroskop. Anato- 

 mie," 1872.) 



