74 MULLER, ON SPH^EROZOUM 



The author then discusses the question of the relationship 

 of the CollosphcBra with Ehrenberg's Polycystina, with the 

 shells of which that of the former exhibits a striking resem- 

 blance, and especially with that of Cenoqyhcera Plutonis, Ehr. 



Mr. Huxley's second species, T. nucleata, he conceives, 

 requires much consideration before its true place can be 

 assigned. But for the present he regards it as advisable to 

 separate T. nucleata with the Physematia of Meyen from the 

 gelatinous bodies with silicious skeletons, and leave the 

 question of their true nature open. With reference, how- 

 ever, to the points of analogy indicated by Huxley between 

 his T. nucleata and Noctiluca, especially in the fact of the 

 motion of the granules in the interior, Prof. Miiller takes 

 the opportunity of noticing certain luminous bodies having 

 the appearance of an encysted Noctiluca miliaris. "These 

 encysted bodies," he says, " constituted the principal luminous 

 animalcules observed at Messina in the autumn of 1853." 

 Free Noctilucce, at that season were not seen there ; and in 

 1849 the same kind of encysted bodies were very common at 

 Nice. The cyst is a perfectly transparent, spherical capsule, 

 with a light-bluish brilliancy at the edge, and appearing 

 like the egg-membrane of some Crustacea. Within this cyst 

 is lodged a body in all respects resembling the Noctiluca 

 miliaris, except that at this time no vibratile filament can be 

 perceived. The Noctiluca-like creature fills the cyst more or 

 less entirely, though occasionally it is much smaller. In this 

 condition the animalcules are luminous without being agitated. 

 When the cysts are examined under the microscope in a 

 small quantity of sea-water, in such a way that during the 

 observation the saline contents are notably increased in conse- 

 quence of the evaporation, a moment speedily arrives when 

 the Noctiluca-like body suddenly contracts itself within its 

 case into a little nodule, that is to say, it contracts upon the 

 yellowish, granular nucleus from which the filamentary strings 

 of the interior proceed. I have noticed this vital phenomenon, 

 not on one occasion only, but in many of the encysted animal- 

 cules." 



" The size of the case is usually from 1-5 to 1-4". But 

 many are far smaller, even down to 1-10". Occasionally, 

 also, instead of a Noctiluca^ cysts may be observed, containing 

 a yellow nucleus 1-24" in diameter, and once I noticed a 

 cyst 2-10" in size, containing, besides this rounded yellow 

 nucleus, quite isolated, an extremely minute Noctiluca-like 

 body. Of the free Noctilucce taken near Heligoland in the 

 autumn, the smallest were 1-20 " and the larger 4-20"' — 7-20 " in 

 diameter. The common variety of form, with a constriction 



