20G F. KEEBLE AND F. W. GAMBLE. 



body. AVc have not yet succeeded iu deteiniiuiiig the chemical 

 nature of these crystals; tbey disappear when the " vacuole" 

 containing tliem is destroyed, as it is by every fixative or 

 reagent we have used. Nevertheless it cannot be doubted 

 that these crystals are products of metabolism, and it seems 

 likely that they are of the nature of excretory nitrogenous 

 substances. Now, these acicular crystals do not occur in the 

 infected green animal. 



Admitting the argument hei'e set forth, the conclusion 

 follows that the green cells, on gaining entrance to the body, 

 take over the business of disposing of the waste products of 

 nitrogenous metabolism. We have learned already that the 

 life of the animal depends on the occurrence of infection, 

 that failing infection the animal ceases to feed and dies, 

 possibly as the result of auto-intoxication by the accumulated 

 waste products. Thus the closeness of the relation between 

 animal and green cells is such that they together constitute, 

 in the green Convoluta roscof f ensis, one organism. 



The conclusions concerning the role of the green cells in 

 utilisino- the nitrogenous waste of the animal as material for 

 proteid synthesis appear to us to throw light on the last 

 phase of the nutrition of the animal. That phase is charac- 

 terised by the digestion of the green cells. In the early 

 stages of its development Convoluta offers to the green cells 

 ample supplies of Avaste nitrogen compounds, the products of 

 its proteid metabolism the materials for which were derived 

 from the reserves in the egg and from the products of 

 dio-estion of solid food. On these excretory nitrogen com- 



O ... 



pounds, and on the product of its own ])hotosynthetic activity, 

 the green cell flourishes, and iu turn furnishes soluble carbo- 

 hydrates to the animal. But when ingestion of solid food 

 ceases thei-e follows a shortage of nitrogenous waste sub- 

 stance. The green cell, adjusted to utilise organic nitrogen, 

 now has only available for proteid synthesis the soluble 

 nitrogen compounds of the sea-water. A dearth of nitrogen 

 compounds available for anabolic processes subvenes. This 

 dearth falls earliest and acutest on the animal. Urged by its 



