KECBNT MEMOIRS ON FRESHAVATER RHIZOPODA. 69 



The rounded nucleus (Avith nucleolus) is very difficult of 

 detection, but it exists (figs. 21 and 22, 7i). 



As toGreeff's view of a homologue to the central capsule 

 whence radiate axial threads of pseudopodia, HertAvig and 

 Lesser are unable to concur in it. The pseudopodia are very 

 fine, granular and readily anastomose, which circumstance 

 Hertwig and Lesser seem very justly to suppose is against the 

 existence of such threads; apart from the difficulty of detect- 

 ing an inner thread Avithin structures themselves, appearing 

 under even very high amplifications as themselves but mere 

 threads. 



The assimilation of the incepted food particles takes place 

 Avithin the vacuoles before alluded to, but a body too large to 

 pass inAvards through the apertures of the shell may be sur- 

 rounded by the protoplasmic substance of the combined 

 pseudopodia, and so digestion be carried on in a vacuole thus 

 appearing as it Avere impromptu. 



HertAvig and Lesser have folloAved out the modes of repro- 

 duction described by CienkoAvski : — After complete self- divi- 

 sion of the body-mass the two portions pass out through an 

 aperture of the shell, and at once establish themselves, first, 

 producing a stipes, folloAved by the appearance of a shell. A 

 further mode is by encysting, the body-mass first breaking 

 up into a number of individual portions, each by and by 

 surrounded by an externally spinulose membrane; after a 

 pause the cysts develope pyriform, nucleated, seemingly 

 biflagellate, zoospores, followed out by Cienkowski to the for- 

 mation of young Clathrulinae. A third process was observed 

 by HertAvig and Lesser, characterised by a repeated sub- 

 division, and, in the formation ofzoospores, it possesses a con- 

 nection on the one hand, Avith the reproduction by encysting, 

 and on the other, in the want of a membrane to the seg- 

 mented portions, it is comparable to simple division. In all 

 cases the authors found the body-mass Avithin the shell 

 broken up into three portions, each of which appeared to 

 give off pseudopodia. Of these fission-products, two were 

 mutually alike in size and smaller than the third, which 

 latter contained approximately about an equal quantity of 

 protoplasm to that of the other tAvo taken together. The first 

 two left the shell simultaneously, or at least one but a very 

 short time subsequent to the other. As already described by 

 Cienkowski, during this process the organisms project an 

 amoeboid process through one of the foramina of the fenes- 

 trate skeleton, causing a figure-of-8- shaped constriction of 

 the body during exit ; this accomplished, the noAV free body 

 forms an elongate ovoid zoospore, Avith a homogenous anterior. 



