94 



17. In the amoebocytes of the Spongillidae food vacuoles are 

 to be found including symbiotic algae in different stages of di- 

 gestion ; so one finds in these vacuoles all normal and „solution" 

 stages of those algae, which I treated repeatedly (p. 42 — 45), 

 viz. : green ones, colourless ones with clear structure, with a shade 

 of structure, without structure, and vague shades of colourless algae. 

 Besides these symbiotic algae one also finds in the vacuoles: 

 diatoms, ordinary algae, bacteria, all sorts of unrecognisable de- 

 tritus and the above mentioned oildroplets, mutually combined as 

 well as with the symbiotic algae. 



18. In sponges newly caught from nature these food vacuoles 

 are rather rare in the tissues (Table 15). Consequently, the 

 sponge in free nature seems to digest only few symbiotic algae 

 and other food particles in this way by vacuoles. 



19. In sponges, which have been for some time in aquaria (with 

 water from the conduit) these food-vacuoles, however, are more 

 numerous (but there does not seem to be much difference then 

 between cultures in the light and in the dark; Table 15); so 

 under these circumstances the sponge proves to digest more food 

 in this way. 



20. In newly caught Spongillae food vacuoles are less numerous 

 in young tissue (branch-tops) than in full-grown (branch-bases) 

 (Table 15). 



21. In newly caught Spongillae the food vacuoles are somewhat 

 more numerous in the tissues of colourless specimina from dark- 

 ness than in those of green ones from light; they seem equally 

 numerous in Ephydatiae (Table 15). 



22. As I mentioned already on p. 42 — 43, most of, not only the 

 normal green symbiotic algae but also of the often mentioned 

 colourless dying- and „solution"-stages of those algae (p. 42 — 45), 

 occur quite free in the protoplasm of the amoebocytes, not in 

 food vacuoles. 



23. The amoebocytes with (green or colourless) symbiotic algae 

 form — as was partly mentioned on p. 16 — the greater majo- 

 rity of the cells of the green and the colourless sponges. The 



