ARCHER ON STEI>HANOSPHiERA PLTJVIALIS (cOBTST). 165 



extremities, so conspicuous in my amoeboid bodies, in the ordinary- 

 primordial cells : it willbe noticed that these are often far more copiously- 

 drawn out into the described filamentous prolongations at one end than 

 at the other, which is more attenuated ; and one end of each of the pri- 

 mordial cells is often drawn much more into one hemisphere of the globe 

 than the other. 



Now, the foregoing remarkable considerations seem to have excited 

 comparatively little notice ; and it is only when such characteristics are 

 evinced so forcibly as that the primordial cells crawl rhizopod-like 

 about, that it strikes us with wonder. The amoeboid bodies described 

 become propelled constantly in one direction, because the pseudopodal 

 processes are given off only at one extremity, and the influx of the gra- 

 nular substance of the mass is of course obliged to follow in that direc- 

 tion. 



But the assumption by the primordial cells of Stephanosphaera of an 

 amoeboid condition is not without a parallel in another volvocinaceous 

 alga. Dr. Hicks has described an amoeboid condition of the "zoospores" 

 of the far more familiar Volvox glohator. * In this organism some of the 

 gonidia increase in size, become colourless; but, containing some brown 

 or reddish particles, become detached from the circumference of the 

 sphere, and acquire the power of protruding and retracting at various 

 points the outer protoplasmic layer (primordial utricle), just like so many 

 true Amoebae. By this power they glide along the inner surface of the 

 sphere. Dr. Hicks enters into some arguments to prove that these are 

 really the modified zoospores or gonidia of the Yolvox, and not true 

 Amoebse which have entered the Yolvox, and have devoured each a zoo- 

 spore equal in size to itself, and then digested it. His arguments, indeed, 

 that it is an actual change of the gonidium itself, seem irrefutable. 



But the amoeboid bodies of Yolvox differ in some particulars from 

 those of Stephanosphaera. In the latter they do not become colourless, 

 as in the former, but retain, as has been stated, their green contents, 

 but in a more disintegrated and loosely granular condition ; they do not 

 contain any reddish particles, as in the case of Yolvox. In the case of 

 Stephanosphaera (as has been stated), the extremities of the amoeboid 

 bodies are definitely distinguishable as an anterior and a posterior end, 

 from the former only of which are the pseudopodal processes protruded, 

 whilst in the amoeboid bodies of Volvox there is apparently no such dif- 

 ferentiation of the ends, and the processes are put forth in any direction. 

 Dr. Hicks has not seen the amoeboid bodies of Yolvox to leave the old 

 sphere and move about in a free condition. In the amoeboid bodies of 

 Stephanosphaera I have not seen any indication of a further change into 

 the oval ciliated bodies described by Dr. Hicks. 



In his very interesting paper alluded to, the same author cites two 

 other cases of vegetable amaeboid bodies observed by him. He describes 

 a change of the cell-contents of the radicles of a moss into an amoeboid 



* " Quart. Journ. of Microscopical Science," vol. viii., N. S. ; " Transactions of the 

 Microscopical Society of London," p. 99, PI. VI. (I860), and vol. ii., N. S., p. 96 (1862). 



