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Recent Progress in our Knowledge of 
however, to doubt the validity of the sexual interpretation of the 
conjugation. He found that in certain cases in Paramoecium 
aurelia and in P. colpoda the so-called spermatic capsule into 
which the nucleolus had become converted, had entirely disap- 
peared without any evident change in the nucleus ; and he con- 
cludes that fecundation of the bodies regarded by Balbiani as eggs 
cannot be here entertained. Indeed, he will not allow that we 
have evidence entitling us to regard the appearance of filaments in 
the interior of the nucleolus as affording any indication of true 
spermatozoa. He offers no explanation of this appearance, but he 
calls attention to the fact that both Balbiani and Stein noticed that 
in transverse division of the Infusoria — a phenomenon with which 
conjugation can have nothing to do — the nucleolus frequently 
enlarges and acquires a longitudinal striation like that of the 
nucleolus in the supposed production of spermatozoa during conju- 
gation. Balbiani maintains that this striation during cleavage is 
only superficial, but it nevertheless affords an argument against 
assigning any more important significance to the very similar ap- 
pearance in the case of conjugation. 
On the whole it would appear that the spermatozoal nature of 
the striae visible in the nucleolus of the conjugating individuals — 
even admitting that these striae represent isolatable filaments — has 
not by any means been proved, while the phenomenon of conjuga- 
tion in the Infusoria would seem to correspond rather with the 
conjugation so well known in many lower organisms, where it takes 
place without being in any way connected with the formation of 
true sexual products. 
In the same memoir the results of observations on some other 
points in the structure and economy of the Infusoria have also been 
given by Butschli. He records the occurrence of minute crystal- 
like laminae in the interior of a marine Infusorium ( Strombidium 
sulcatum) rendered remarkable by a conspicuous girdle of tricho- 
cysts which surround its body (PI. CXVIII., Figs. 1 and 1 a). The 
crystal-like corpuscles seem to be of the nature of starch, for on the 
application of iodine they assume a beautiful violet colour. It does 
not appear from Butschli ’s account of these bodies that they have 
not been introduced from without, and the chief interest of the 
observation seems to be in the discovery of an amyllaceous body 
assuming a crystalline form. He had previously met with similar 
bodies in a parasitic Infusorium ( Nyctotherus ovalis), as well as in 
a Gregarina (G. blattarum). 
He also describes, under the name of Polyhricos Sivartzii (Fig. 2), 
a new Infusorium which he frequently found in the fjords of the 
south coast of Norway and in the Gulf of Kiel, and which he regards 
as especially interesting, from the fact that with a true infusorial 
organization it contains, irregularly distributed in the outer layer 
