1894 THE MICROSCOPE. 27 



In some sponges the sexes are claimed to he distinct. 

 Both sperm as well as germ cells are claimed to develope 

 from wandering amoeboid cells which first exhibit lively 

 amoeboid movements, but later on pass into a resting 

 stage. This, as already indicated, is strongly advocated 

 by Prof. Haeckel. Kent, however differs radically from 

 this view, and knows only the following process : One or 

 more sponge zooids, having lived its or their allotted 

 span, become quiescent, take on an amoeba form, become 

 a cell in which spores are generated, which, when suf- 

 ficiently advanced, pass out through the osculae. The 

 cell looses its shape, and what are called " swarm-gem- 

 mules" appear. These, when sufficiently developed, show 

 on their upper part flagellated collared cells with unde- 

 veloped cells beneath. Ultimately they settle on some 

 firm substance and begin sponge life like their parent. 



In the case of commercial sponges, artificial propaga- 

 tion of sponges, by cutting from live specimen, has been 

 successfully attempted under the auspices of the Italian 

 government. Pieces about an inch square were cut con- 

 taining part of the exterior of the subject. These were 

 tied to sticks and submerged in the proper locality. 

 This process proved a success, but had to be abandoned 

 bv reason of serious objections from fisherman. 



Slides for Sale.— The .Jersey Biological Station (P^ngkiiul) 

 will i^suc a quarterly publication and a series of 14 niicroscoi)- 

 ical preparations of the rare and the less renown marine organ - 

 isins. The text will describe the slides and give notes upon ma- 

 nipulation. The price is S5.25 for the year. Only 75 copies 

 will be issued. 



To Write on Glass. — Make an ink by dissolving in a warm 

 water bath ; bleached shellac, 10 parts ; Venetian turpentine, 5 

 parts ; oil of turpentine, 5 parts. When dissolved, add 5 parts 

 of lampblack. TJse \yith a pen the san:>e as other inks. 



