50 ON THE STRUCTURE OF NOCTILUCA MILIARIS. 



According to M. Suriray the Noctiluca is a spherical gela- 

 tinous mass, provided with a long filiform tentacle or ap- 

 pendage, presenting a moutli, an oeso])liagus, one or many 

 stomachs and ramified ovaries, and thus possessing a certain 

 complexity of organization De Blainville confirmed Suri- 

 ray 's account, and placed Noctiluca, without douht most erro- 

 neously, among the Diphydae. On the other hand, Van Beneden 

 Verhaeghe and Doydre, denying the relation of Noctiluca 

 with the Acalephse — and conceiving its organization to be 

 of a much inore elementary character — relegated it to the 

 Rhizopoda. 



To this doctrine M. de Quatrefages also attaches the 

 weight of his authority in his valuable essay ' Observations sur 

 Ics Noctiluques^ published In the Annales des Sciences Nat, 

 for 1850. M. de Quatrefages does not admit the existence 

 of any true mouth or intestinal canal, and considers that the 

 so-called stomachs are nothing but ^vacuoles' similar to tlK)se 

 observed in the Rhizopoda and Infusoria. 



In a short memoir published in Wiegmann's Archiv. for 

 1852, however, that excellent and most accurate observer, 

 M. Krohn, carried the subject a stage further, and showed 

 that the organization of Noctiluca is more complex than has 

 been supposed. Krohn carefully describes and figures the 

 mouth of Noctiluca and the long vibratile ciliwn, which he 

 was the first to observe, proceeding from it, Krohn draws 

 particular attention to the oval body first described by 

 Verhaeghe, which he considers to be the homologue of 

 the ^nucleus' oi the infusoria; and describes the ejection 

 of faecal matters. Arranging the Noctiluca among the 

 Protozoa, Krohn points out some interesting structural 

 analogies with ActinO])hrys and Paramecium. 



I will now proceed to detail the results of my own ob- 

 servations. 



Noctiluca miliaris (Plate V. figs. 1, 2) may be best de- 

 scribed as a gelatinous transparent body, about l-60th* of an 

 inch in diameter, and having very nearly the form of a peach ; 

 that is to say, one surface is a little excavated and a gioove 

 or depression runs from one side of the excavation half way to 

 the other pole {echancrure, Quatrefages. Frauenhnsendhnliche 

 Einhucht, Krohn). Where the stalk of the peach might be, 

 a filiform tentacle, equal in length to about the diameter of 

 the body, depends from it, and exhibits slow wavy motions 

 when the creature is in full activity. I have even seen a 



* The extremes of size are given by Krohn as 1-7 — 1 millimetre 

 = 1-170 — 1-25 inch about. 



