I270 BULLETIN OF THE BUREAU OF FISHERIES. 



modia has probably transformed itself in whole or in great part into a thin 

 uniform incrustation. It is best now to transfer the plate to the open water. 

 My practice has been to tie such plates to the inside of galvanized-wire boxes, 

 and to hang the boxes in a large live-box. 



In the course of a week it will be found that the incrustation has transformed 

 itself into a functional sponge with pores, oscula, well-developed canal system, 

 and flagellated chambers. The steps in this gradual differentiation may be 

 followed by examining the sponge at intervals under the microscope. The 

 differentiation goes on, but at a slower rate, in preparations kept continuously 

 in laboratory dishes or aquaria. While the sponge incrustation is quite thin, 

 the currents of water and vibrations of the flagella in the flagellated chambers may 

 be observed with a high power. For this purpose small incrustations grown on 

 cover glasses are the best. 



Until the past summer it was a question whether sponges produced in this 

 way would continue to grow and would develop the skeleton characteristic of 

 the species. If they would not, it was clear that the method had no value for 

 economic sponge culture. And so, early in July, I again visited the Beaufort 

 laboratory and with the help of my assistant, Mr. R. R. Bridgers, started some 

 Alicrociona plasmodia on glass slides and oyster shells. It was possible for me 

 to remain at the laboratory only two weeks, but Mr. Bridgers took charge of the 

 sponges and continued to start other plasmodia at intervals during July and 

 August, conducting his experiments with great care and skill. 



Mishap of course overtook some of the cultures; but scores of them grew 

 perceptibly during the summer and by the first of September a large nimiber 

 had developed the skeleton of the adult with the characteristic spicules and the 

 homy columns projecting up from the basal skeletal plate. What was equally 

 gratifying was that the sponge in many cases had not only spread and thickened 

 and developed the species-skeleton, but had also developed quantities of repro- 

 ductive bodies. These lay scattered in the deeper part of the incrustation, 

 plainly visible to the eye. I have not yet made a sufficiently precise histological 

 examination of these bodies to determine whether they are egg larvae or asexual 

 masses. The whole appearance of the sponges grown in this way, some six 

 weeks old, is quite like that of normal Microciona of incrusting habit. 



Looking from the utilitarian standpoint at this latter method of growing 

 sponges, it is not at all inconceivable that it may at some time be of direct 

 economic value. The ease with which quantities of sponge cells may be had and 

 the opportunity afforded of attaching them to any desired object are consider- 

 ations which encourage such an idea. Going farther afield from present-day 

 practice and looking to the futvue, the method suggests itself as one of the possible 

 means of altering the specific characteristics of sponges and improving races. In 



