Fan. 26, 1882] : 
station at Kakoma, in 32° 29’ E., and 5° 47’S., in the plateau 
which begins at the boundary of Ugogo with the Mpwapa 
heights. The letters contain a good deal of information on the 
country and the people, the fauna, flora, and climate. Dr. 
Stecker gives an account of his Abyssinian journey, to which 
we have already referred. Herr Flegel gives a long account of 
his journey from Rubba, on the Niger, north to Sokoto and 
back, between October 1880 and April 1881. His map contains 
much new and useful information on the country traversed. 
Finally there are some letters from Herren Pogge and Wiss- 
mann, who had reached Malange in May, and hoped to be at 
Kimbundo in June, 
FURTHER RESEARCHES ON ANIMAIS 
CONTAINING CHLOROPHYLL}? 
[It is now nearly forty years since the presence of chlorophyll 
in certain species of Planarian worms was recognised by 
Schultze. Later observers concluded that the green colour of 
certain infusorians, of the common fresh-water hydra, and of the 
fresh water sponge was due to the same pigment, but little more 
attention was paid to the subject until 1870, when Ray Lankester 
applied the spectroscope to its investigation. He thus consider- 
ably extended the list of chlorophyll-containing animals, and 
his results are summarised in Sachs’ Botany (Eng, ed.). His 
list includes, besides the animals already mentioned, two species 
of Radiolarians, the common green sea-anemone (Anthea cereus, 
var. smaragdina), the remarkable Gephyrean, Bonellia viridis, a 
Polychete worm, Chefopferus, and even a Cru-tacean, /dotea 
viridis. 
The main interest of the question of course lies in its bearing 
on the long-di-puted relations between plants and animals ; for, 
since neither locomotion nor irritability are peculiar to animals, 
since many insectivorous plants habitually digest solid food, since 
cellulose, that most characteristic of vegetable products, is practi- 
cally identical with the tunicin of Ascidians, it becomes of the 
greatest interest to know whether the chlorophyll of animals 
preserves its ordinary vegetable function of effecting or aiding 
the decomposition of carbonic anhydride and the synthetic pro- 
daction of starch. For although it had long been known that 
Euglena evolved oxygen in sunlight, the animal nature of such 
an organism was merely thereby rendered more doubtful than 
ever. In 1878 [had the good fortune to find at Roscoff the 
material for the solution of the problem in the grass-green 
planarian, Convoluta Schultziz, of which multitudes are to be 
found in certain localities on the coast, lying on the sand, 
covered only by an inch or two of water, and apparently basking 
in the sun. It was only necessary to expose a quantity of these 
animals to direct sunlight to observe the rapid evolution of 
bubbles of gas, which, when collected and analysed, yielded 
from 45 to 55 per cent. of oxygen. Both chemical and histo- 
logical observations showed the abundant presence of starch in 
the green cells, and thus these planarians, and presumably also 
Hydra, Spongilla, &c., were proved to be truly ‘‘ vegetating 
animals.” 
Being at Naples early in the spring of 1879, I exposed to sun- 
light some of the reputedly chlorophyll-containing animals to be 
obtained there, namely, Loxellia viridis and Jdotea viridis, while 
Krukenberg had meanwhile been making the same experiment 
with Goneliia and Anthea at Trieste. Our results were totally 
negative, but so far as Govel/ia was concerned this was not to be 
wondered at, since the later spectroscopic investigations of Sorby 
and Schenk had fully confirmed the opinion of Lacaze-Duthiers 
as to the complete distinctness of its pigment from chlorophyll. 
Krukenberg, too, who follows these investigators in terming it 
bonellein, has recently figured the spectra of Anthea-green, and 
this also seems to differ considerably from chlorophyll, while I 
am strongly of the opinion that the pigment of the green crus- 
taceans is, if possible, even more distinct, having not improbably 
a merely protective resemblance. 
It is now necessary to pass to the discussion of a widely distinct 
subject—the long-outstanding enigma of the nature and functions 
of the ‘‘ yellow cells” of Radiolarians. These bodies were first 
so called by Huxley in his description of Zhad/assicolla, and are 
small bodies of distinctly cellular nature, with a cell wall, well- 
defined nucleus, and protoplasmic contents saturated by a yellow 
» Abstract of a paper “‘On the Nature and Functions of the ‘ Yellow 
Cells’ of Radiolarians and Ccelenterates,’’ read to the Royal Society of 
eouer on January 14, 1882, and published by permission of the 
ouncil,. 
NATURE 
393 
pigment. They multiply rapidly by transverse division, and are 
present in almost all Radiolarians, but in very variable number. 
Johannes Muller at first supposed them to be concerned with 
reproduction, but afterwards gave up this view. In his famous 
monograph of the Radiolarians, 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 Vogt in Velel/la and Porgita, Later 
he made the remarkable discovery that starch was present in 
notable quantity in these yellow cells, and considered this as 
confirming his view that these cells were in some way related to 
the function of nutrition. In 1871 a very remarkable contribu- 
tion to our knowledge of the Radiolarians was published by 
Cienkowski, who strongly expressed the opinion that these yellow 
cells were parasitic algee, pointing out that our only evidence of 
their Radiolarian nature was furnished by their constant occur- 
rence in most members of the group. He showed that they 
were capable not only of surviving the death of the Radiolarian, 
but even of multiplying, and of passing through an encysted and 
an amoeboid state, and urged their mode of development and 
the great variability of their numbers within the same species as 
further evidence of his view. 
The next important work was that of Richard Hertwig, who 
inclined to think that these cells sometimes developed from the 
protoplasm of the Radiolarian, and failing to verify the observa- 
tions of Cienkowski, maintained the opinion of Haeckel that the 
yellow cells ‘‘ fur den Stoffwechsel der Radiolarien von Bedeu- 
tung sind.” In a later publication (1879) he, however, hesitates 
to decide as to the nature of the yellow cells, but suggests two 
considerations as favouring the view of their parasitic nature— 
first, that yellow cells are to be found in Radiolarians which pos- 
sess Only a single nucleus, and secondly, that they are absent in 
a good many species altogether. 
A later investigator, Dr. Brandt of Berlin, although failing to 
confirm Haeckel’s observations as to the presence of starch, 
has completely corroborated the main discovery of Cienkowski, 
since he finds the yellow cells to survive for no less than two 
months after the death of the Radiolarian, and even to continue 
to live in the gelatinous investment from which the protoplasm 
had long departed in the form of swarm-spores. He sums up 
the evidence strongly in favour of their parasitic naiure, 
Meanwhile similar bodies were being described by the investi- 
gators of other groups. Haeckel had already compared the 
yellow yells of Radiolarians to the so-called liver-cells of Vélella ; 
but the brothers Hertwig first recalled attention to the subject in 
1879 by expressing their opinion that the well-known ‘‘ pigment 
bodies ” which occur in the endoderm cells of the tentacles of 
many sea-anemones were also parasitic algee.. This opinion was 
founded on their occasional occurrence outside the body of the 
anemone, on their irregular distribution in varicus species, and 
on their resemblance to the yellow cells of Radiolarians. Buy 
they did not succeed in demonstrating the presence of starch, 
cellulose, or chlorophyll. The last of this long series of re- 
searches is that of Hamann (1881), who investigates the similar 
structures which occur in the oral region of the Rhizostome 
jelly-fshes. While agreeing with Cienkowski as to the parasitic 
nature of the yellow cells of Radiolarians, he holds strongly 
that those of anemones and jelly-fishes are unicellular glands. 
In the hope of clearing up these contradictions, I returned 
to Naples in October last, and first convinced myself of the 
accuracy of the observations of Cienkowski and Brandt as 
to the survival of the yellow cells in the bodies of 
dead Radiolarians, and their assumption of the encysted and 
the amceboid states. Their mode of division, too, is tho- 
roughly algoid. One finds, not unfrequently, groups of three 
and four closely resembling Protococcus. Starch is invariably 
present ; the wall is true plant-cellulose, yielding a magnificent 
blue with iodine and sulphuric acid, and the yellow colouring- 
matter is identical with that of diatoms, and yields the same 
greenish residue after treatment with alcohol. So, too, in 
Velella, in sea-anemones, and in medusz ; in all cases the pro- 
toplasm and nucleus, the cellulose, starch, and chlorophyll, can 
be made out in the most perfectly distinct way. The failure of 
former observers with these reactions, in which I at first also 
shared, has been simply due to neglect of the ordinary botanical 
precautions. Such reactions will not succeed until the animal 
tissue has been treated with alcohol and macerated for some 
hours in a weak solution of caustic potash. Then, after neu- 
tralising the alkali by means of dilute acetic acid, and adding a 
weak solution of iodine, followed by strong sulphuric acid, the 
