248 SUMMARY OF CURRENT RESEARCHES RELATING TO 



stantly colourless, specimens, apparently young, of Nebela hohemica, a 

 coloured species, may be found colourless, as occurs in the EuglypMdte 

 and in Arcella. In the shell of Nebela hursella alone were perforations 

 found, viz. two on each of the narrower sides; their function is, 

 perhaps, to admit water into the spaces inside the shell, between the 

 protoplasmic attachments of the body (called epipodia by Taranek), 

 as they occur under similar conditions in Hyalosphenia, and the 

 admission of water would have advantages for the animal. Taranek 

 is unable to corroborate Leidy's statement that the smallest tests have 

 the largest chitinous plates. In occasional examples of Nebela 

 hohemica and coUaris the plates are reduced to small granules, scattered 

 over the surface, or they may be absent altogether, and the chitinous 

 membrane left bare, or encrusted with foreign bodies. The plates 

 consist of amorphous silica, as they resist combustion and weak 

 acids and alkalies ; strong sulphuric acid dissolves them slightly ; 

 they are firmly imbedded in the chitinous membrane, except in 

 Quadrula. 



With regard to their origin, the author comes to the conclusion 

 that they are formed by the animal itself, from their resemblance to 

 those of the Euglyphidce, which are undoubtedly thus produced. The 

 thickest plates are those of Lecquereusia, the thinnest those of 

 Quadrula. The chitinous membrane is susceptible of staining, and 

 thus, and from the mode in which foreign bodies are attached to it, 

 evidently itself constitutes the only cementing substance employed ; 

 it sometimes projects outside the margins of the plates, and can here 

 attach foreign bodies to itself. The sarcodic body of the Nebelidce 

 has the definiteness of form common to all the Monoihalamia. As 

 observed in specimens kept without food, the ectosarc is completely 

 hyaline and structure- and colour-less ; it is viscous, the outer part 

 more so than the inner, which thus, and by acquisition of granules, 

 gradually passes into the endosarc. The endosarc has usually a pale 

 yellow colour, and contains refractive bodies (microsomata) of two 

 sizes. The nucleus is relatively large, and remains constantly at the 

 back of the body, in the shell; a nucleolus is only occasionally 

 noticed, has a dark or blueish colour, and a globular form ; one or 

 more nucleoli (up to five) may occur. A contractile vacuole was 

 always observed, usually one or two ; in Lecquereusia, Meleopera, and 

 Quadrula three occur, closely associated. The author frequently 

 finds in Nebelidce chlorophyll masses derived from food, but never 

 showing signs of being produced by the animal itself. The pseu- 

 dopodia are formed by the streaming forward of the clear ectosarc, 

 which divides into five to nine cylindrical lobes, the body at the same 

 time becoming further removed from the inner wall of the test. The 

 epipodia, when the animal is extended, form long filamentous pro- 

 cesses of ectosarc. 



The animals live chiefly in peat-moss water, and prefer it when 

 it is low ; they either swim, with the mouth downwards, by move- 

 ments of the extended pseudopodia (five to twelve in number), or 

 creep by means of fewer pseudopodia, which attain the length of 

 the shell, and have a flattened form ; they drag the shell after 



