ON THE RADIOL ARIA AS AN ORDER OF THE PROTOZOA. 273 
cell wall before the dissolution of the mother-cell.” (Memoir 
page 145.) But such a dictum becomes sheer nonsense after its 
having been gravely laid down on the authority of Cienkowski 
that these yellow cells (described in the page preceding as being 
66 very characteristic of the whole of the Radiolaria , except some 
Accmthometra forms ”), 44 were found vigorously multiplying in 
dead Radiolaria ; ” and that Cienkowski 44 suspected that they 
may be parasitic organisms ; ” whilst Hertwig, it is said, op- 
posed Cienkowski’s view on account of the constancy of the 
presence of the yellow cells in the Radiolaria , on which Mr. 
Mivart, with singular naivete, remarks : — 44 But undoubted 
parasites are present with remarkable constancy in many higher 
animals, while several difficulties disappear if we regard them as 
parasites. It would (he says) first account for no other satis- 
factory explanation of their origin having been arrived at ; 
secondly, for their greatly varying number ; thirdly, for their 
survival and increase amidst the decomposition of the indi- 
viduals in (sic) which they live ; and lastly, it would explain 
the anomaly of unicellular animals containing true cells.” 
(Memoir p. 145.) 
At p. 144 it is stated that 44 certain peculiar structures, 
namely, the yellow cells , are very characteristic of the Radio- 
laria, being found in all , except some Acanthometra forms. 
They are nucleated, and their protoplasmic contents are en- 
closed in a distinct membrane .” Whilst, in reference to the 
question as to whether unicellular animals can contain true 
cells within themselves, as part and parcel of their organization, 
Mr. Mivart continues as follows : 44 Without venturing to ex- 
press an opinion on this controversy, I would place on record 
that Hertwig has come to the conclusion that a multinucleolate 
cell is potentially multinucleate, as a multinucleate cell is 
potentially multicellular ; and thus we get a transition from uni- 
cellular to multicellular organisms. . . The multicellular nature 
of the Radiolarians now depends entirely on the normal nature 
of the yellow cells, and on the correctness of the observations of 
the centripetal cell-groups of Physematium . As has been said, 
neither of these phenomena can be reposed on as being cer- 
tainly of the nature of true cells , forming part of the normal 
organization of the Radiolarians in which they have been 
found ; but even if they are so, and if we are compelled, there- 
fore, to regard Radiolarians as multicellular, their multicellu- 
larity is of a radically different kind from that of any of the 
Metazoa ; and none of their parts, whether true cells or not, 
have any valid claim to the denomination of a tissue. (Memoir, 
pp. 182, 183.) 
We shall see hereafter that their true cell nature is very 
distinctly maintained, nevertheless ; or if not so, that the absence 
new SERIES, VOL. II. NO. VII. T 
