SPONGE CULTURE. 591 
Fogarty * has observed that the presence of a moderate current is most useful. 
These results are evidently explained by the simple fact, known to all, that the 
waters of a current are better aerated and contain a richer fauna. In such 
places, consequently, a more abundant supply of nourishment is available and 
from it the bottom animals, like the sponges, profit more or less directly. It 
may be easily understood that the presence of a certain current improves the 
conditions of the surroundings in which the sponges grow and facilitates thus 
the success of experiments in sponge culture. However, too swift currents 
should be avoided. The aim of sponge culture is the furnishing of skeletons of 
sponges easy to sell, hence we must not forget that the sponges grown in very 
agitated waters have a coarse skeleton and that this diminishes their commercial 
value. This observation was made a long time ago; Aristotle says that sponges 
differ according to their place of growth, ‘“‘the ones by their softness and the 
others by their coarseness,”’ and he thus explains this fact: ‘‘The softest sponges 
are those which come from deep, always quiet, waters.’ Similar observations 
have been made by modern fishers of sponges,’ and the reason is easily found. 
We meet here one of the applications of the principle of Lamarck concerning 
adaptation to surroundings. The réle of the spongeous skeleton of a Euspongia 
or a Hippospongia is to insure a relative rigidity to the body of the animal; it 
is quite natural that there should be established a certain automatic balance 
between the firmness of the skeleton and the shocks or pressure which the sponge 
has to bear. This is a hypothesis which Keller * has very well elucidated. It 
might not be quite wise to accept all the deductions he made from it, but the 
primary idea of his work seems to me perfectly correct. We can not as yet prop- 
erly orient the phylogenic tree of the spongeous species. In certain kinds the 
spongeous matter is doubtless in part an ancestral persistence; in others it may 
have been acquired more recently, and we have no means of distinguishing be- 
tween these two species. Hence, the ideas of Keller should not be discredited, 
because species generally inhabiting relatively deep and calm waters are pro- 
vided with rather firm spongeous skeletons. 
It would be interesting to know, also, without departing from this question, 
whether the individuals developed in agitated waters owe the firmness of their 
skeleton to a difference in the nature of their spongeous matter (greater impreg- 
nation of salts, for example, different physical condition, etc.) to a greater 
quantity of solid particles in their primary fibers, to a greater thickness of 
these fibers, or to a lesser flexibility of secondary fibers. We know that Len- 
an Rathbun. 
b See observations of M. Crozat, made on the coasts of Provence, in: L’Industrie des péches aux 
Colonies, by Darboux, Stephan, Cotte, and Van Gaver, p. 220, vol. I. 
¢ Zeitschrift fiir die wissenschaftliche Zoologie, vol. L11, and Festschrift der Universitat Ziirich, 
Nageli and KGlliker, 1890-91. 
