RECENT MEMOIRS ON FRESHWATER RHTZOPODA. 308 



After a copious description of and dissertation on the 

 various views as to the numerous nuclei of this form, Schulze 

 passes to the pseudopodia with their " axes." The curious 

 mode of ending of the latter passing in through the endosarc, 

 discovered by GreefF, is confirmed by Schulze, as well as by 

 Hertwig and Lesser. Max Schultze recognised them but as 

 a peculiar form of contractile plasma, not as spines, in which 

 Hertwig and Lesser, as mentioned above, coincide; but 

 GreefF, followed by Eilhard Schulze, regards them as delicate, 

 cylindrical " spines," comparable to " skeleton-pieces," 

 whilst GreefF described them (as mentioned) as penetrating 

 into the endosarc. Schulze avers that normally they 

 only reach as far as that region, and, as it were, stand 

 thereon. 



This is certainly, so far as I myself can see, all they ordi- 

 narily appear to do, nor do they even seem to have the power 

 to be retracted into it. When an example of this form is 

 first transferred from a bottle and placed on a slide it often 

 appears with the pseudopodia " tossed^' and curved about 

 every way, " dishevelled" looking, nay, occasionally inoscu- 

 lating, but soon they begin to stand out stiff and " trim." 

 Were these axile threads rigid " spines," comparable to those 

 of, say, an Acanthocystis, this could hardly happen. 



Schulze, indeed, attributes to them a great elasticity, a 

 capability of being bent and even, under some circumstances, 

 being fused. They appear to consist of an organic albumi- 

 noid substance. M. Schultze had observed two axes in one 

 pseudopodium, indicating, of course, the fusion of two ad- 

 joining and previously independent pseudopodia. 



After describing the pulsating vacuoles the author proceeds 

 to the description of the observations touching the reproduc- 

 tion of this form. 



The author in the first place refers to the older observations 

 of simple division into two and of the fusion into one of 

 several individuals, both phenomena not unfrequent — nay, 

 the latter can be artificially effected. Thus Cienkowski 

 narrates the result of keeping on a slide in a drop of water an 

 Actinosphserium composed of several fused individuals, as 

 consisting in the withdrawal of the pseudopodia, the disap- 

 pearance of the alveolar nature of the body, the whole be- 

 coming dark, finely-granular mucus, interspersed with 

 numerous vacuoles, and surrounded by a clear, thickly-fluid 

 envelope ; in about seven hours the mass broke up into 

 several dark balls, each surrounded by a colourless mucous 

 envelope, acquiring subsequently a sharp contour surrounded 

 by a membrane standing off at some distance ; the remaining 



VOL. XVI.-— NEW 8ER. U 



