NOTES AND MEMORANDA. 
361 
of the usage proposed, a motion that the Congress should attempt to 
settle the question by requesting its general adoption met with so 
much opposition that it was withdrawn. 
Trichodonopsis paradoxa (Clap.). — The position, as regards classi- 
fication, of this genus of Ciliate Infusoria, is said by the ‘ Micrographic 
Dictionary ’ to be doubtful. It resembles externally one of the 
Vorticellina, but is covered with well-develoj)ed cilia. The species 
T. paradoxa inhabits in myriads the intestines of Cyclostoma elegans. 
M. A. Schneider contributes a note in regard to it to ‘ Comptes 
Rendiis.’ He says “ it is common amongst the Cyclostomata of the 
neighbourhood of Poitiers. Its study has developed some interesting 
facts (complementary to those of Claparede and Stein), which I will 
briefly describe. 
The cuticle presents over the whole of its surface, a very flnely 
punctated appearance, resulting from the presence beneath it of an 
uninterrupted layer of little rods of circular section, disposed in 
‘ palisades,’ as may be seen in profile views. They are most easily 
observed on the basilar membrane of the disk. They resemble, in 
form and position, trichocysts, although without urticating filaments, 
and although they exist, as I have said, on the basilar membrane, 
which is constantly naked, without cilia or other appendages. 
The problematical organ in the form of a solid cap, regarded by 
Claparede as muscular, and left undetermined by Stein, is the nucleus. 
It is hollowed out on one side ; and in the notch, or opposite to it, is 
a small, very distinct spherical nucleolus. 
This shows — 1st, that the problematical organ and its satellite 
(nucleolus) are the only parts of the body which give with acids and 
colouring substances the characteristic reactions of the nuclear matter ; 
2nd, that several Trichodinae, especially Neritilia Jluviatilis, have a 
nucleus and a nucleolus, which correspond topograj^hically to the 
organs which we consider as identical in the Trichodonopsis ; 3rd, that 
the problematical organ, occasionally single, is sometimes double, 
triple, or quadruple ; its division may indeed go farther, and it is 
not uncommon to find in the body six or seven tolerably large sphe- 
rules, and from thirty to eighty smaller granules, representing alto- 
gether the nucleus of which they give the reactions ; the nucleolus 
appears to remain undivided whilst the nucleus undergoes this frag- 
mentation : it is thus shown that the problematical organ j)lays th^e 
same part here as the nucleus of the infusoria in reproduction by 
rejuvenescence ; 4th, the impossibility of calling that a nucleus which 
Claparede and Stein have wished to consider as such in Trichodo- 
nopsis. 
This organ, indeed, which surrounds the digestive apparatus, does 
not fix colouring reagents ; its structure is sj^ecial ; its thickness is 
most commonly occupied by more or less bulky calculi ; in fact, its 
very existence is not constant, for it is wanting in a whole category of 
individuals which are distinguished at the same time, by slight dif- 
ferences in the conformation of the superior extremity, and chiefly by 
an entirely diflerent arrangement of the digestive apparatus ; and this 
in such a degree that there is a real dimorphism in relation to the 
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