1887.] NATURAL SCIENCES OF PHILADELPHIA. 165' 



Great pleasure and profit may be attained in the same direction,, 

 by germinating the statoblasts or gemmules under artificial condi- 

 tions, and studying the development of the young sponges by the 

 aid of as high powers of the microscope as the ingenuity of each 

 student may bring to bear upon the subject. I take the liberty to 

 copy from the Ann. and Mag. Nat. Hist. 1882, p. 365, Mr. Carter's 

 directions for germinating statoblasts, which will be found valuable. 

 " To obtain the young spongillse it is only necessary to get a portion 

 of an old living specimen bearing statoblasts, and, having taken 

 out a few (six to twelve) of the latter, to roll them gently between 

 the folds of a towel to free them from all extra material as much 

 as possible, place them in a watch glass so as not to touch each 

 other, with a little water, in a saucer or small dish filled with small 

 shot to keep the saucer upright and, covering them with a glass shade, 

 transfer the whole to a window bench opposite to the light. In a few 

 days the young Spongilla may be observed (from its white color) is- 

 suing from the statoblast and gluing the latter as well as itself to the 

 watch glass, when it will be ready for transfer to the field of the micro- 

 scope for examination, care being taken that it is never uncovered by 

 the water, which may be replenished as often as necessary ; but of 

 course the object-glass (when I inch with high occular is used for 

 viewing the minute structure) must admit of being dipped into the 

 water without sufl^usion of the lens." 



My own first experience in the propagation of fresh water sponges 

 may prove instructive in various ways. Late in the autumn of the 

 year 1879, in a pond within the "Centennial Grounds," Philadel- 

 phia, I found for the first time a living sponge. It was a vigorous, 

 branching specimen of Spongilla lacustris, charged with gemmules 

 in all parts of its structure. A fragment firmly attached to a stone 

 was taken home and placed in a gallon "specie-jar" with water, in 

 the hope, begotten of inexperience, that it would continue to grow, 

 exhibit its inflowing and exhalent currents, etc. On the contrary, 

 and as I now know, almost necessarily, it died, and in a few days 

 the water became insupportably foul. It was changed and another 

 trial made, which resulted as before. This time the jar was thorough- 

 ly cleansed ; the stone with the attached sponge was taken out and 

 held long under a flowing hydrant before it was replaced in the jar, 

 which was now left in an outer shed and, very naturally, forgotten. 

 Weeks passed and winter came on, and one severe night the water 

 in my jar was frozen solid and the vessel fractured. I supposed 



