379 
of Edinburgh, Session 1881-82. 
while Krukenherg had been making the same experiment with 
Bonellia and Anthea cereus at Trieste.* Our results were totally 
negative, but so far as Bonellia was concerned this was scarcely to 
be wondered at, since the later spectroscopic investigations of 
Sorby and Schenck had corroborated the opinion of Lacaze- 
Duthiersf as to the complete distinctness of its pigment from 
chlorophyll. Krukenherg, too, who follows Sorby in terming it 
bonellein , has recently figured the spectra of Anthea-green, J which 
also differs considerably from chlorophyll, while I am strongly 
of opinion that the pigment of the green Crustaceans (Idotea, &c.), 
is even more distinct, having not improbably a merely protective 
resemblance. I have also exposed to light the green shrimp 
( Palcemon viridis), the green polychsete annelid ( Phyllodoce viridis ), 
Chcetopterus Valenciennesii, and a small greenish Tectibranchiate 
mollusc, Dolabella sp., but as I had expected, without finding the 
slightest evolution of oxygen take place. 
We may now pass to the discussion of the proper subject of the 
present paper, the long outstanding enigma of the nature and 
functions of the “yellow cells” of Radiolarians, &c. These 
bodies, which were first so called by Huxley in his description of 
ThalassicoTla , are small bodies of distinctly cellular nature, with a 
cell- wall, well-defined nucleus, and protoplasmic contents saturated 
by a yellow pigment. They multiply rapidly by transverse fission, 
and are present in almost all Kadiolarians, but in very variable 
number. Johannes Muller at first supposed them to be concerned 
with the reproduction of the Radiolarian, but afterwards gave up 
this view. In his famous monograph, Haeckel § suggests that they 
are probably secreting cells or digestive glands in the simplest form, 
and compares them to the liver-cells of Amphioxus, and the liver- 
cells described by Yogt,|| in Velella and P 'or pit a. Later, he made 
the remarkable discovery that starch was present in notable quan- 
tity in these yellow cells, and considered this as confirming his view 
* 
* Vergleichend Physiologischc Studien, Bd. I. Abth. 1, p. 167.' 
t “ Anat. de la Bonellie,” Ann. d. Sci. Nat. Zool., 4 Ser. tom. x. 
X Pergl. Physiol. Studien , Bd. I. Abtheil 2, p. 76. 
§ Die Radiolarien , p. 136. 
|| “Sur les Siphonophores,” &c., Inst. Nat. Genevois, tom. i. 1854. 
3 G 
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