THE PREPARATION OF MATERIAL. 281 



the spicules deposited upon the slip, heat the slip gently to make 

 sure of the drying, cover the spicules with a drop of balsam, add the 

 cover glass, and the preparation is complete. 



V. On "Germinating" the Gemmules. "To obtain the young 

 spongillae, it is only necessary to get a portion of an old living speci- 

 men bearing statoblasts (gemmules), and, having taken out a few 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) issuing from the statoblast (gern- 

 mule), and gluing the latter as well as itself to the watch glass, when 

 it is ready for transfer to the field of the microscope for examination, 

 care being taken that it is never uncovered by water, which may be 

 replenished as often as necessary." H. J. CARTER, ESQ., of Devon- 

 shire, England, in Annals and Magazine of Natural History for 1882, 

 p. 365. 



" If a few of them (gemmules) are removed from a fresh sponge, 

 placed in an open stage tank (or watch glass) covered with water 

 (preferably rain water), and protected from dust and too rapid evapo- 

 ration by a cover of common glass, and placed upon a window ledge 

 but not in direct sunlight, the following phenomena may be confi- 

 dently expected. 



" We are supposed to be working with gemmules heavier than water, 

 beneath which they are allowed to rest quietly. If in a few days or 

 hours some of the gemmules are found fixed where they lie, it is 

 probable that germination has begun. On removing the preparation 

 to the stage of the microscope, the instrument being fixed in vertical 

 position, the initial stages of the development of a sponge can be 

 daily or hourly watched under low powers of magnification. 



" A creamy white granular film first appears, and gradually surrounds 

 the gemmule, then widens, spreading irregularly in various direc- 

 tions, reminding one of the appearance of a giant amoeba. At first 

 nearly uniform in texture and density, it will soon be seen that the 

 interior portion is more compact than the superficies, a very delicate 

 film being set off around and over it, puffed up at one subcentral 

 point into a greatly elongated rounded cone, open at the extremity. 

 Here at this early stage is a complete sponge. The water with its 

 contained nutriment is already being drawn in through almost in- 

 visible pores, and, after feeding the young cells, is thrown out at the 



