NOCTILUCA MILIARIS. 13 



is somewhat remarkable that the tail, or tentacle, is next formed . 

 the secondary stage is that the divided nuclei remove far apart, 

 and looking at the animal from the under side, we shall see that a 

 division is commencing ; in the next stage the form assumes that 

 of the dumb-bell, but with a decided thickening in the middle. 

 In the further development the self-division becomes complete, 

 and the two individuals are held together like the Siamese twins 

 by a single cord. The process of division is then completed by 

 the rupture of the connecting portion, and the final absorption of 

 the abnormal part. The whole operation takes place within a few 

 days, for in a gathering made by a writer on this subject, on 

 March yth numerous double specimens were seen ; on the 13th 

 only two double specimens could be found held together by a 

 slight band, and after that date no double specimens could be 

 seen. 



Cienkowski states that even a small portion of the protoplasm 

 of a mutilated Noctiluca will reproduce an entire animal. Multi- 

 plication by fission, beginning in the enlargement and ultimate 

 separation of the two halves of the nucleus, has also been 

 observed. Another form of non-sexual reproduction commences 

 in an encysting process, not unlike the swarm spores of many 

 Protophytes. The flagellum and tentacle disappear on the 

 narrowing up of the mouth, which finally closes, the median 

 groove is no longer seen, and the result is that the animal becomes 

 simply a hollow sphere. Then follows the elongation of the 

 nucleus, its transverse constriction, and the division of the halves, 

 with the exception that each is connected to the other by a bridge 

 of network. This is repeated over and over again till you have 

 a mass of some five hundred gemmules. Sometimes there is a 

 detaching of the mass as a whole, and sometimes, and perhaps I 

 should add more commonly, the gemmules detach themselves 

 one by one, commencing at the edge of these colonial habitations, 

 and proceeding to the centre. In the early stage the gemmules 

 are simply spheres of the monad type, and contain their nucleus, 

 contractile vesicle, and tentacle ; then follows the mouth, and the 

 formation of the permanent flagellum and tentacle. The true 

 position in the animal kingdom of the Noctiluca is relegated to 

 the flagellate infusoria. 



