30 BULLETIN OF THE BUREAU OF FISHERIES. 



Fig. 15. Slide preparation kept eight days in live box. Photograph made by transmitted light 

 from balsam mount stained lightly in hsemalura. Canal system well developed. Characteristic spicules 

 have appeared. X20. 



Fig. i5. Vertical section of slide preparation kept six weeks in live box. Photograph from stained 

 balsam mount. Characteristic skeleton has developed. Reproductive bodies present. X73J. 



Fig. 17. Slide preparation photographed in alcohol by reflected light. Plasmodial masses have 

 partially transformed into thin incrustation. X|. 



Fig. 18. Cover-glass preparation photographed by transmitted light. Plasmodia formed by con- 

 tinued imion of sponge cells have transformed into incrustations. XiJ. 



Fig. 19. Small part of cover-glass preparation of metamorphosed Plasmodium, showing canals 

 with very abundant flagellated chambers and scattered spicules. Xioo. 



Fig. 20. Cover-glass preparation photographed by transmitted light in alcohol. Most of the plas- 

 modial masses have metamorphosed into incrustations. A few, two especiallj', persist as thick rounded 

 bodies which appear as very dark areas in the photograph. Xif. 



Plate IV. 

 Microciona prolifera. 



Fig. 21. Freshly dissociated cells (pressed out through bolting cloth). From a living preparation. 

 Camera, Zeiss 2 mm. Comp. Oc. 6. X666|. 



Fig. 22. From preparation shown in figure 21, but 10 minutes later. Many cells have combined 

 to form masses. Camera, Zeiss 2 mm. Comp. Oc. 6. X666f . 



Fig. 23. Plates, reticula, and compact masses of the pressed-out tissue. XiJ- 



Fig. 24. From the preparation shown in figures 21 and 22, about one hour after cells were pressed 

 out of sponge. Mass of regenerative tissue formed by fusion of smaller masses. Camera, 2^iss 2 mm. 

 Comp. Oc. 6. X666§. 



Fig. 25. Plasmodium in shape o' peiforated plate formed by pressed-out tissue. XisJ- 



Pl.iTE V. 



Fig. 26. Microciona prolifera. Sponge with oscular tube, subdermal cavities, etc., developed 

 from mass formed by gradual fusion of teased-out tissue. X 13 J- 



Fig. 27. Microciona prolifera. Lobed mass formed by continued fusion of teased-out tissue. X60. 



Fig. 28. Plasmodia of Microciona and Lissodendoryx. Lissodendoryx tissue stippled. Microciona 

 tissue unstippled. Xi6§. 



Fig. 29. Plasmodia of Microciona and Lissodendoryx. Lissodendoryx tissue stippled. Microciona 

 tissue unstippled. Xi6|. 



Fig. 30. Plasmodia of Microciona and Styloiella. The upper irregular mass is the Stylotella tissue, 

 which rests upon the ovoidal Microciona mass. Xi6§. 



Fig. 31. Microciona prolifera. Small plasmodial mass in early stage of metamorphosis. Collen- 

 chyma has been differentiated in several places at the periphery. X80. 



Fig. 32. Plasmodia of Microciona and Lissodendoryx. Lissodendoryx plasmodia are stippled. 

 Microciona plasmodia in unstippled water color. X30. 



Fig. 33. Stylotella. From a cover-glass preparation, showing plasmodial masses combined to 

 form a reticulum. X i6|. 



