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of a nuclear vesicle , which is adopted by Mr. Mivart as the most 
prominent and important feature in six-sevenths of the whole of 
the Radiolaria , is contra-indicated in every one of these six- 
sevenths (with exception of the Polycystina , one group which, 
as I have never ceased to contend, ought not to be associated 
with the other groups, but with the Foraminifera in the first 
Rhizopod order), in consequence of this very deficiency as 
regards a definite nucleus — that is, a truly encapsuled nuclear 
mass.* 
But speculative philosophy and naivete go yet a stage 
further ; for Mr. Mivart informs us that his deus ex machina, 
“ Haeckel, speculates as to the possibly hepatic nature of the 
yellow cells, considering it to be not unlikely that they may be 
an incipient form of liver. But in the first place these cells 
may, as has been said, be parasitic ; and secondly, a liver is, as 
it were, a comparatively late result of tissue formation, and 
could hardly exist in the admittedly tissueless Protozoa ! ” 
(Memoir, p. 158.) 
In 1863 I pointed out, for the first time, that the so-called yel- 
low cells , as also more or less perfectly colourless, but in other 
respects perfect homologues of them, are present throughout all 
the Rhizopodal families, both oceanic and fresh water ; this 
statement being based on long personal experience. At the 
time indicated, they had been observed by others only in three 
pelagic families, namely, the Polycystina , the Thalassicollina , 
and the Acanthometrina ; their brilliant yellow tint in the 
pelagic families being regarded as their distinguishing character, 
until it was shown by me that absolutely identical bodies (see 
PI. VI., figs. 1-3, 5, 6), in all save colour, are common, as before 
stated, to the entire Class. Their office had, moreover, until 
then been either altogether unrecognized, or, so far as I am 
aware, referred to only more or less incidentally as in some 
manner connected with reproduction. 
It was in the course of a laborious day-by-day series of 
observations on the fresh-water and littoral Rhizopods, extend- 
ing over the greater part of the years 1863 and 1864, that I 
was enabled to compare and trace clearly and consecutively the 
mode of origin of these remarkable bodies, and to prove beyond 
all reasonable doubt that they constitute a true reproductive 
organ, formed either directly (as may be witnessed in the Fora- 
minifera of our own shores) by the aggregation into minute 
spheroidal masses of granular, probably germinal, particles, 
which, up to the period of this change taking place, are more 
or less uniformly distributed through the sarcode mass generally : 
or, indirectly , by the subdivision of the contents of the granular 
nuclear mass itself, without, however, acquiring in any instance 
* See my classification at the close of this article. 
