564 
NATURE 
[March 31, 1870 
ordinary echinida are invested. This type bears a strong 
resemblance to the very singular fossil from th white chalk, 
described by the late Dr. S. P. Woodward, under the name of 
Echinothuria floris. Specimens were also obtain. d, both in the 
first and third cruises, of a most interesting clyseastroid, which 
is closely allied to the i7/u/aster—specially characteristic of the 
later chalk.* These constitute only a sample of the interesting 
novelties belonging to this group, which our explorations brought 
to light. 
Besides further additions to the remarkable group of vitreous 
sponges, which were made in the area over which the Globigerina- 
mud extends, a peculiar and novel form of sponge was found to 
be one of the most generally diffused inhabitants of the cold 
area. This sponge is distinguished by the possession of a firm 
branching axis, of a pale sea-green colour, rising from a spreading 
root, and extending itself like a shrub or a large branching gor- 
gonia. The axis is loaded with siliceotis spicules ; and spicules 
of the same form are contained in the soft flesh which clothes it. 
The foraminifera collected in the Porcupine expedition present 
features of no less interest, though their scale is so much smaller. 
The enormous mass of Globigerina-mud (sometimes almost pure, 
sometimes mixed with sand) that everywhere covers the deep-sea 
bottom in the region explored, save where its temperature is 
reduced nearly to the freezing-point, may be judged of from the 
fact that in one instance the dredge brought up half-a-ton of it 
from a depth of 767 fathoms. The resemblance of this deposit 
to chalk is greatly strengthened by the recognition of several 
characteristically cretaceous types among the foraminifera scat- 
tered through the mass of G/odigerine of which it is principally 
composed ; as also of the Yanthidia, frequently preserved in 
flints. Not many absolute novelties presented themselves among 
the foraminifera that form true calcareous shells ; the chief point 
of interest being the occurrence of certain types of high organi- 
sation at great depths, and their attainment of a size that is only 
paralleled in much warmer latitudes, or in the Tertiary or yet 
older formations. This is especially the case with the Cristel- 
larian group, which has a long geological range ; and also with 
the Milioline, of which specimens of unprecedented size presented 
themselves. The most interesting novelty was a_ beautiful 
Orbitolite, which, when complete, must have had the diameter 
of a sixpence, but which, from its extreme tenuity, always broke 
in the process of collection. Of Arenaceous Foraminifera, how- 
ever, which construct tests by cementing together sand-grains, 
instead of producing shells, the number of new types is such as 
seriously to task our power of inventing appropriate generic 
names. Many of these types have a remarkable resemblance to 
forms previously known in the chalk, the nature of which had not 
been recognsied. Some of them throw an important light on the 
structure of two gigantic Arenaceous types from the upper green- 
sand, recently described by the speaker and Mr. H. B. Brady, an 
account of which will appear in the forthcoming part of the 
‘* Philosophical Transactions ;” and there is one which can be 
certainly identified with a form lately discovered by Mr. H. B. 
Brady in a clay-bed of the carboniferous limestone. 
The question now arises, whether—as there must have been deep 
seas in all geological periods, and as the changes which modified 
the climate and depth of the sea-bottom were for the most part 
very gradual—we may not carry back the continuity of the accu- 
mulation of Globigerina-mud on some part or other of the ocean 
bed into geological epochs still more remote ; and whether it has 
not had the same large share in the production of the earlier 
calcareous deposits, that it has undoubtedly had in that of the 
later. The foraminiferal origin of certain beds of the carboni- 
ferous limestone, for example, appears to be indicated by the 
presence of Glodigerine, long since observed by Professor Phillips 
in sections of them, as well as by the fact just stated. The sub- 
crystalline character of these rocks cannot be regarded as in any 
way antagonistic to such an idea of their origin, since it is per- 
fectly well known that all traces of the organic origin of calcareous 
rocks may be completely removed by subsequent metamorphism, 
—as in the chalk of the Antrim coast. 
What is the source of nutriment for the vast mass of animal 
life covering the abyssal sea-bed, is a question of the greatest 
biological interest. That animals have no power of themselves 
generating the organic compounds which serve as the materials 
* This was believed at the time to be an entirely new discovery ; but since 
the return of the Porcupine we have learned that a type generically, if not 
specifically, the same, had been obtained by Count Pourtales during his 
most recent dredgings in the Gulf of Mexico, and had been described by 
Mr, Alex. Agassiz under the name Pourtalesia miranda. 
of their bodies—and that the production of these materials from 
the carbonic acid, water, and ammonia of the inorganic world, 
under the influence of light, is the special attribute of vegetation 
—is a doctrine so generally accepted, that to call it in question 
would be esteemed a physiological heresy. There is no difficulty 
in accounting for the alimentation of the higher animal types, 
with such an unlimited supply of food as is afforded by the 
Globigerine and the sponges in the midst of which they live, and 
on which many of them are known to feed. Given the Protozoa, 
everything else is explicable. But the question returns,—on 
what do these Protozoa live? 
The hypothesis has been advanced that the food of the abyssal 
Protozoa is derived from diatoms and other forms of minute 
plants, which, ordinarily living at or near the surface, may, 
by subsiding to the depths, carry down to the animals of the 
sea-bed the supplies they require. Our examination of the 
surface-waters, however, has afforded no evidence of the exist- 
ence of such mycrophytic vegetation in quantity at all sufficient 
to supply the vast demand; and the most careful search i 
the Globigerina-mud has failed to bring to light more than ‘a 
very small number of specimens of these siliceous envelopes of 
Diatoms, which would most assuredly have revealed themselves 
in abundance, had these Protophytes served as a principal com- 
ponent of the food of the Protozoa that have their dwelling- 
place on the sea-bed. Another hypothesis has been suggested, 
that these Protozoa which are so near the border of the vegetable 
kingdom, may be able, like plants, to generate organic com- 
pounds for themselves, manufacturing their own food, so to 
speak, from inorganic materials. But it is scarcely conceivable 
that they could do this without the agency of light; and as it is 
obviously the want of that agency which excludes the possibility 
of vegetation in the abysses of the ocean, the same deficiency 
would prevent animals from carrying on the like process. 
A possible solution of this difficulty, offered by Professor 
Wyville Thomson in a lecture delivered last spring, has 
received so remarkable a confirmation from the researches made 
in the Porcupine expedition, that it may now be put forth 
with considerable confidence. It is, he remarked, the dis- 
tinctive character of the Protozoa, that ‘‘they have no special 
organs of nutrition, but that they absorb water through the 
whole surface of their jelly-like bodies. Most of these animals 
secrete exquisitely-formed skeletons, sometimes of lime, some- 
times of silica. There is no doubt that they extract both of 
these substances from the sea-water, although silica often exists 
there in quantity so small as to elude detection by chemical tests. 
All sea-water contains a certain amount of organic matter in 
solution. Its sources are obvious. All rivers contain a large 
quantity ; every shore is surrounded by a fringe, which averages 
about a mile in width, of olive and red sea-weeds ; in the 
middle of the Atlantic there is a marine meadow, the Sargosso 
Sea, extending over 3,000,000 of square miles ; the sea is full 
of animals which are constantly dying and decaying; and the 
water of the Gulf Stream, especially, courses round coasts where 
the supply of organic matter is enormous. _ It is, therefore, quite 
intelligible that a world of animals should live in these dark 
abysses: but it is a necessary condition that they should chiefly 
belong to a class capable of being supported by absorption 
through the surface, of matter in solution ; developing but little 
heat, and incurring a very small amount of waste by any manifes- 
tation of vital activity. According to this view, it seems highly 
probable that at all periods of the earth’s history some form of 
the Protozoa—rhizopods, sponges, or both—predominated over 
all other forms of animal life in the depths of the sea; whether 
spreading, compact, and reef-like, as in the Laurentian and 
Palaeozoic Loz00n; or in the form of myriads of separate organisms, 
as in the Globigerine and Ventriculites of the chalk.”* 
During each cruise of the Porcupine, samples of sea-water ob- 
tained from various depths, as well as from the surface, at stations 
far removed from land, were submitted to the Permanganate test, 
after the method of Prof. W. A. Miller, with an addition suggested 
by Dr. Angus Smith for the purpose of distinguishing the organic 
matter in a state of decomposition from that which is only de- 
composable ; with the result of showing the uniform presence of 
an appreciable quantity of matter of the latter kind, which, not 
having passed into a state of decomposition, may be assimilable 
as food by animals, being, in fact, protoplasm in a state of 
extreme dilution, And the careful analyses of larger quantities 
collected during the third cruise, which have been since made by 
* ‘The Depths of the Sea,” a lecture delivered in the theatre of the Royal 
Dublin Society, April 10, 1860, 
