RECENT MEMOIRS ON FRESHWATER RHIZOPODA. 355 



mens one half green, one half colourless, the line of change 

 sharply marked off; this species, too, varies a good deal in 

 size. The same amount of variation in these respects may 

 occur, possibly, in H. myriopoda, 



Heterophrys spinifera, Hertwig and Lesser.^ (Fig- 14 ) 



is a freshwater form, distinguished from the preceding by 

 the comparatively greater length of the linear processes 

 ("spines") of the outer envelope, as well as of the pseu- 

 dopodia. It certainly appears, judging from the figure, 

 to be a distinct form, yet its differences difficult to define, 

 for I venture to suggest the character of the supposed 

 large interval between the body-mass and the granular 

 and then fimbriated outer region, as compared to the pre- 

 ceding, may not be founded in fact. If we compare it in 

 this regard with Heterophrys varians, Schvlze,^ Ileliojjhrys 

 variabilis, Gieeff, we see an outer envelope of considerable 

 depth, devoid, it is true, of any of those capillary processes 

 (spines, Hertwig and Lesser) at its own periphery, and that, 

 towards the periphery of the inner sarcode body (except in 

 one of Greeff's figures), it is quite as hyaline as Hertwig and 

 Lessor's figure shows for H. spinifera. I do not think it can be 

 maintained that in H. varians the outer (living) substance is 

 restricted to the granuliferous concentric distant border, with 

 vacancy, or only water, intervening between it and the body- 

 mass ; certainly in examples I once myself took I should never 

 have fancied the pellucid interval, permeated here and there 

 by pseudopodia, to be non-living and empty (save of water), 

 in fact, just as little as one would suppose the granular- 

 looking and striate outer portions of the very thick gelatinous 

 envelopes to certain algal forms to be separated from the 

 plant within by a vacant interval, merely because it appears 

 homogeneous and hyaline. In Hertwig and Lesser's figure 

 of their form* the granular portion gradually fades off in- 

 wardly, without showing any line of demarcation limiting 

 this supposed distant " skeleton" inwardly. 



In accordance with their views, however, the authors 

 describe the body of this form as freely poised in the middle 

 of the distant granular stratum, forming a hollow sphere, in 

 which it is sustained in position solely by the pseudopodia. 

 They consider a protoplasmic composition of this " spine- 

 bearing" granular layer as out of the question, as they record 

 it did not yield to sulphuric acid. This, no doubt, is a very 

 important observation ; but, on the other hand, 1 have no 



' Hertwig and Lesser, loc. cit., p. 215, t. v, f. 



