THE FKESH-WATER SPONGE. 
135 
characters of the sponges coincide without difficulty with those 
of vegetable structure, inasmuch as their supposed animal 
characters, automatic ciliary movement, swarming young (or 
locomotive gemmules), and spermatozoids, and some contrac- 
tility, as also a movement of the juices, have been recognised in 
both kingdoms.’' 
As to certain movements of the sponges, as in CharacecB and 
some of the Algoe or lower plants, I had long before attributed 
them not improbably to the action of endosmosis and exos- 
mosis. So Ehrenberg observes : If the sponges be animals, 
their nourishment must be conveyed from in front and without, 
through apertures capable of being closed ; if they be plants, 
the nourishment must be supposed to pass from the root- like 
base outwards and forwards by endosmose and exosmose.” And 
this action can, I apprehend, solve some other conditions of the 
sponges. 
The learned author of the ‘‘ Infusionsthierchen” very re- 
cently writes : I see no inducement at present* to give up 
the opinion already repeatedly expressed by me, that sponges 
cannot be described as animals.” 
As regards myself. Professor Williamson says : Mr. J. Hogg 
some years ago noted various phenomena, which led him to 
conclude that it {Spongilla) was a plant. He specially observed 
that its green colour was largely dependent upon the action of 
light — a plant-like feature which had much weight with him 
and those who, like him, believed the Spongilla to be a vegeta- 
ble form.” This fact certainly gave me strong cause for that 
belief ; but I will also add that other facts, which are not named 
by the Professor, and which were developed in the examination 
of the river-sponge, tended likewise to the same view ; and these 
were, the presence of starch granules in some specimens of 
Spongillce, as recorded by Mr. Carter ; also the existence of 
iodine in the sea-sponges ; the disengaging of the numerous 
bubbles of gas (oxygen) under the brightest sunshine, by the 
living mass of Spongilla ; and the green chromule, or colouring 
matter, of the river-sponge being so similar to that in green 
Confervce and many other plants. 
The numerous spicula of sponges, although of remarkable 
and varied forms, do by no means prove them to be of an 
animal nature, because the like crystalline minute particles, 
called EaphideSjf are secreted in a great many vegetable sub- 
* See December 1866, Monatsbericht der Berlin. Akad. der Wissen- 
schaften.” 
t Vide Lin. Trans, vol. xviii. p. 398, for a notice of Rapliides and their 
composition. These vegetable crystals are chiefly composed of oxalate of 
lime, and magnesia ; some occasionally of phosphate of lime. Also in others, 
carbonate of lime is present, and probably carbonate of magnesia. 
