YELLOW-BROWN CELLS OF CONVOLUTA PARADOXA. 473 
GENERAL CONCLUSIONS. 
1. C. paradoxa occurs within a narrow belt of seaweed 
on the shore. It exhibits tidal migrations within this belt. 
The migratory movements are the resultant reactions to the 
various directive stimuli to which, in its changing environ- 
ment, it is subject. 
2. The ege laying and hatching are periodic. The periods 
synchronise with those of the neap-tides. 
3. The eggs and just-hatched larvee contain no yellow- 
brown cells. Preserved from infection, e.g., by hatching 
and maintaining in filtered sea-water, C. paradoxa remains 
free from yellow-brown cells (G. & K.). 
4. By bringing uninfected larve in contact with seaweed 
from the Paradoxa zone infection is induced (G. & K.). 
5. The infecting organism is an alga different from 
Zooxanthella of Radiolarians ; its free stage is unknown. In 
the ingested state it is characterised by many chloroplasts, a 
colourless anterior end, and by the possession of fat globules 
in its colourless protoplasm. 
6. Once introduced into the body of C. paradoxa the 
infecting organism multiples rapidly. . 
7. The fat-globules of the algal cell are food-reserves. 
They arise as the result of the photosynthetic activity of the 
algal cells. 
8. The reserve-fat of the algal cells is translocated from 
those cells to the animal tissues, and serves these tissues as 
- food-material. 
9. The ingested, yellow-brown, algal cell becomes, physio- 
logically, an integral part of the animal, contributing towards 
its nutrition, and incapable of a separate existence. 
10. The yellow-brown algal cells are indispensable to the 
animal. Uninfected animals fail to develop. 
11. Nevertheless, starved animals digest their algal cells 
till no trace of these cells remains. Such disinfected animals 
