and Reproductive Phenomena of the Amoeban Rhizopods. 461 



and the singular features the specimens assumed, a fresh supply 

 was obtained from the same locality. This was retained in its 

 natural state, and on examination was found to contain specimens 

 in every respect similar to those described as occurring in the 

 mixed material. The encysting process was thus shown to be 

 in no way dependent on conditions artificially produced, but to 

 be the result of an effort on the part of the creature to furnish 

 itself with nutritive matter during the development of the sarco- 

 blasts into which the sarcode-mass is destined, under these cir- 

 cumstances, to resolve itself*. 



The first step, as already stated, consisted in the extrusion of 

 all foreign particles besides the diatom -frustules — the vacuolar 

 cavities in which the latter were enclosed being, for a time, dis- 

 tinctly visible and often of great size (see PI. VIII. figs. 12 & 13), 

 but gradually disappearing as their fluid contents became 

 absorbed. Finally, all trace of pseudopodia, nucleus, contractile 

 vesicle and villous organ vanished ; all motion to and fro, and 

 the pseudocyclosis dependent on it, ceased; and the diatoms 

 seemed to be merely surrounded by a layer of coarsely gi'anular 

 but otherwise homogeneous sarcode, the outline of which was 

 preserved by a distinct capsular wall, whilst its shape was 

 dependent on the disposition and number of the enclosed 

 frustules. 



It may be remembered that (in the ' Annals^ for June, p. 435) 

 it was stated that the bodies to which I had given the name of 

 sarcoblasts, and described as being " distinctly granular, nearly 

 homogeneous throughout, and devoid of cell-wall,^^ in all proba- 

 bility " perform some important part in the process of repro- 

 duction, and are identical in all save colour with those of the 

 Foraminifera, Polycystina,Thalassicollid0e, and some other pelagic 

 families ;^' whilst in a still more recent paper (^ Annals,^ August, 

 p. 125) I mentioned that " in the earliest recognizable condition in 

 which I had found the Polycystina and Acanthometrina occurring 

 as independent free-floating organisms, their rudimentary shell 

 or framework had invariably been enveloped in bodies precisely 

 resembling the sarcoblasts of the mature forms," and that to 

 this extent their share in the reproductive process had been 

 traced out. 



The views then expressed receive the most complete verifica- 

 tion from what takes place iu these Amoeba. The movements both 



* It is worthy of record that no organisms but Diatoms have been foimd 

 by me in these ^mceia-cysts, notwithstanding the circumstance that, when 

 decomposition was commencing in the pools, many of the lower vegetable 

 forms, such as Closterium, Volvox, Gonium, and the host of minute phj^to- 

 spores that have so erroneously been regarded as mature Desmidiacece 

 were in profusion. 



