
AUGUST 5, 1915] 
NATURE 
633 

claimed to be exhibited by some of the Foraminifera 
in the construction of their shells, a claim which has 
been, and is, denied by several very distinguished 
zoologists, and admitted, with some reservations, by 
others no less distinguished.44 There are limits to 
what is known, but I refuse to admit that there 
are limits to what is knowable. As Prof. MacBride 
has justly observed: ‘‘To put forward an unknown 
entity as the cause of phenomena which we cannot 
unravel is not to explain, but in reality to give up the 
attempt at explanation.’’ ** 
The method in which the arenaceous Foraminifera 
collect and adjust the materials from which they build 
their marvellous shells is obscure, and though a light 
begins to dawn upon the process it would take too 
long to go into the matter on this occasion. Surface 
tension no doubt plays an important part in the opera- 
tion, but surface tension will not account for the 
mysterious fact that certain species, such as, to take a 
single instance especially, Haplophragmium ag glu- 
tinans, incorporate into their shells fragments of heavy 
gem minerals such as magnetite, garnet, and topaz, 
which are not by reason of their specific gravity to be 
found in the same sand-strata as the relatively light 
quartz-grains which are mainly used in the construc- 
tion of the shell. The common Verneuilina poly- 
stropha of our shores exhibits this phenomenon also 
to a remarkable degree. It is, however, the intelli- 
gence (and I use this word with a full sense of the 
responsibility which I incur in using it) displayed in 
the manipulation of the material whieh compels the 
attention of the biologist. We are all familiar with 
the beautifully built tubes of the Caddis worm, and 
some of the marine worms build tubes of no less 
remarkable ingenuity, as, for instance, Amphictene, 
and one local variety of this worm constructs its tube 
as neatly as a bricklayer building a wall out of frag- 
ments of sponge-spicules of a carefully selected size. 
But these are Metazoa, higher animals, endowed with 
organs and senses. The Foraminifera, I must repeat 
for emphasis, are unicellular creatures without any 
differentiated organs or even structure of any kind 
whatever. 
Take the common arenaceous form, Psammosphaera 
fusca, which builds itself into a roughly agglutinated 
house of sand grains. There is no selection here. 
There is none in the variety P. testacea, which uses 
only the shells of dead and living Foraminifera—it 
uses them because it has nothing else to use; but 
P. parva (Fig. 6), finding itself by its small size and 
free habit liable to suffocation in the ooze on which it 
lives, builds its house round a catamaran spar formed 
of a long sponge-spicule, which buoys it up upon the 
mud surface. Another species, P. rustica, builds in 
the spaces of a tent-pole arrangement of such spicules 
—several individuals frequently combining to form a 
mutually supporting mass. This creature fills in the 
triangular spaces between the main tent-poles with 
broken spicules of successively graduated lengths, and 
when it arrives at an «wkward terminal space finds 
and incorporates a truncated triaxial sponge-spicule 
to fill in the angle. F 
It is when we come to the devices employed by the 
Foraminifera for their protection from living foes, or 
the forces of nature, that their purposive intelligence 
becomes the most phenomenal. Many of the larger 
and doubtless more succulent forms are peculiarly 
liable to attack from parasitic worms—an_ elaborate 
study of which has been made by Prof. Rhumbler.** 
41 E. Heron-Allen, ‘‘On Purpose and Intelligence in the Fo-aminifera,” 
Proc. Zool. Soc., p. 1069. London, rorq. 
42 B. W. MacBride, in Nature, vol. xciv., p. 304. November ro. 1914. 
43, L. Rhumbler, ‘‘ Beitrage zur Kenntniss der Rhizopoden,” Zeitschr. 
Wiss. Zool., vol. lvii., p- 589. 18c¢4. 
NO. 2388, VOL. 95] 


A striking instance of this occurs in the case of 
Crithionina pisum, which has a softly agglutinated 
shell, which is often found (as in one of the specimens 
exhibited) bored by worms. Certain individuals have 
arrived at protecting themselves with a chevaux de 
frise of sponge-spicules, and these we never find, so 
far as our experience goes, suffering from these 
attacks. Haliphysema ramulosa is another easily 
attacked species, and it protects its aperture with a 
similar defensive apparatus. The same _ protective 
investment is assumed by Hyperammina ramosa, a 
species which ramifies in a most remarkable manner, 
so much so that Earland once constructed for me 
a Christmas greeting slide out of its. many vagariant 
forms. (The ‘selection’? in this case is rather that of 
Earland than of the Rhizopod.) 
The genus Marsipella, of which the most. familiar 
form is M. cylindrica, is built up of sponge-spicules 
set. parallel to its axis, and ‘is excessively friable, 
perfect specimens being very seldom found. It con- 
sists of a simple tube affording an easy prey to 
parasitic worms. It has consequently learnt to protect 
itself with a crown of spines, which keep out these 
intruders. But some individuals, to which we have 
given the specific name M. spiralis, have made the 
same discovery as did the prehistoric genius who 
invented string. They increase their power of resist- 
ance to shock by twisting their spicules into a left- 
handed spiral, by. which'means their power of. resist- 
ance is enormously’ increased.** ; 
But probably the zenith of purpose and. intelligence 
is reached by the genus Technitella, a genus named by 

Fic. 6.—Psammosphaera parva, Flint. 
Cauon Norman—the Little Workman—with good 
cause. The most familiar species, T. legumen, builds 
its shell apparently of sponge-spicules set parallel 
to its axis. The accidental smashing of a specimen, 
however, revealed to us the fact that only the outer 
layer of spicules is thus disposed. The inner layer is 
set at right angles to the outer, thus producing the 
nearest approach to the woof and warp of a textile 
fabric possible in so rigid a material as sponge-spicules. 
This is clearly seen in a highly magnified fragment 
of a broken shell. The genus reaches its highest 
development of purposive selection, however, in our 
species T. thompsoni, which, out of the vast and 
heterogeneous mass of material at its disposition, 
selects only the anchor-plates of a particular kind of 
Echinoderm, which it cements together at their edges 
with an invisible cement, and thus constructs what is 
certainly one of the most decorative, and certainly the 
most highly perforated shell in existence.*° 
In the presence of the phenomena which I have 
exhibited before you this evening there are zoologists 
who aver that there is no such thing as purpose or 
intelligence to be postulated as a motive for the 
behaviour, not only of the Protozoa, but even of much 
higher orders of animal life. Jules Fabre, who has by 
consent assumed the purple among the _historio- 
44 EK. Heron-Allen and A. Earland, ‘‘On some New Astrorhizide and 
their Shell Structure,” Journ. R. Micr. Soc., p. 382. _ 1912. 5 
45 FE. Heron-Allen and A. Earland, ‘‘On a New Species of Technitella 
from the North Sea,’” Journ. Quekett Micr. Club, ser. 2, vol. x., Pp. 423- 
1909. 
