198 



PHOTOZOA. 



mation. The buds separate themselves from the membrane and 

 become free as small spores, with nucleus and cylindrical appendage, 

 to assume the Noctiluca form under circumstances which have as 

 yet not been closely observed. According to Cienkowski, conjugation 

 may take place between normal forms as well as between encysted 

 forms. 



The Noctiluca owe their name to their power of producing light, 

 a power which they share with numerous sea animals, such as 

 Medusae, Pyrosoma, etc. The light proceeds 

 from the peripheral layer of protoplasm. 

 Under certain conditions they rise from the 

 deep to the surface of the sea in such enor- 

 mous numbers as to cause wide tracts of the 

 sea to give out a reddish light. It is after 

 sunset, and especially in the evening, when 

 the sky is overcast, that we get the beautiful 

 phenomenon of the phosphorescent sea. 



The species distributed in the North Sea 

 and in the Atlantic Ocean is Noctiluca 

 uiiliaris. Nearly allied is the Mediterranean 

 Leptodiscus medusoides K. Hertwig. 



Order 2. CILIATA.* 



Ciliated Infusoria with 'mouth and anus, 

 sarcode body of complicated structure (with 

 endoplasm and exoplasm\ with nucleus and 

 paranucleus (nucleolus}. 

 FIG 137 S 1 / /OH ch'a m-ti'm ^ e l com tive cuticular appendages that 

 (after stein), (seen from ^e most frequently meet with are slender 



ventral side). Wz, Adoral .,. -, . . /., ,-, T , ,. < 



zone of cilia; C, contractile clha > whlch ften COVer the whole Surface f 



vacuoie ; N, nucleus ; N>, the body in close rows, and give it a striped 



paranucleus; A, anus. -r,, .,. ,, 



appearance. I he cilia are usually stronger m 



the region of the mouth, and are here grouped so as to form an 

 adoral zone of large cilia, which, during swimming, causes a whirl- 

 pool, and conducts the matter which serves as nourishment into the 

 mouth (fig. 137). This adoral zone is more highly developed in 

 fixed Infusoria such as the bell animalcule, the surface of which 

 has no uniform coating of cilia. In these animals there are 



Fr 

 180 



* Besides Ehrenberg, Claparedc, Lachmann. Biitschli, 1. c., compare especially 

 . Stein, " Der Organismus der Infusionsthiere," I. and II., Leipzig, Ib59 and 



