Mr. H. J. Carter on the Freshwater Sponges of Bombay. 89 
endosmose ?), become globular, and after a few hours burst. At 
the time of bursting, their visible contents, which consist of a 
mass of germs, occupying about two-thirds of the cavity of the 
cell, subside, and afterwards gradually become spread over the 
bottom of the vessel in which they are contained. They are of 
various diameters below the 5,4;5th part of an inch (PI. III. fig.6a), 
which is the average linear measurement of the largest, and ap- 
pear to be endowed with the power of locomotion in proportion 
to their size; that is to say, that while the largest scarcely do 
more than turn over now and then, as the globules of the blood, 
the most minute are incessantly moving backwards and forwards, 
here and there, and assembling in crowds around the larger 
ones. 
If a germ about the ;,),5th part of an inch in diameter be 
selected for examination, it will be observed to consist of a dis- 
coid, circular, well-defined translucent cell, which is green or yel- 
lowish green at the circumference, but becomes pale and colour- 
less towards the centre. This cell appears to be again surrounded 
by a colourless transparent capsule, the nature of which is un- 
known to me, and I am not altogether certain of its real exist- 
ence. 
The green colour is hardly perceptible in germs measuring less 
than the zgggath part of an inch in dianieter; below this they 
all appear to be colourless. 
A few days after the germs have been eliminated, they for the 
most part become parcelled out into insulated groups, and united 
together by a semi-transparent mucilage. In this position the 
contents of the largest, which resemble the endochrome of the 
cells of Confervee, undergo a change, becoming nebulous towards 
the circumference, pellucid in the centre, and then nebulous 
throughout. The largest germs then disappear gradually, and 
their disappearance is followed by a successive development of 
proteans or active polymorphic cells. These proteans for the 
most part do not exceed, in their globular or passive state, the 
diameter of the germs which have disappeared, and a successive 
development of them continues to take place from the contents 
of the same seed-like body for two or three months after their 
elimination. There are some proteans present, however, much 
larger, exceeding even the ,i,th part of an inch in diameter, 
which always make their appearance under the same circum- 
stances, but they are not so numerous ; the most numerous are 
those which average in diameter the =;\,5th part of an inch. The 
form assumed by the latter when in a state of activity is that of 
the diffluent protean (Plate IV. fig. 1 e), which in progression 
throws out globular or obtuse expansions of its cells ; that of the 
largest, the denticulated protean (fig. 1d), which in progression 
