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 jjfoifih part of an inch (PI. III. fig.6«), 

 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 ^V o tn P art °^ an mcn ■ 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 yuio o tn P art °f an mcn m diameter ; 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 Confervse, 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 7^0^ P ar ^ °f 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 ^—^ ^th 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. 1 d), which in progression 



