476 



On a Unicellular Green Alga. 



[Feb. 28, 



studied in pure culture, that there was a marked increase in growth 

 when this carbohydrate was added to their culture medium, though 

 no quantitative experiments were made to measure any difference in 

 assimilation. 



The general features of the assimilation of nitrogen, on the other 

 hand, and its subsequent history displayed by Chlorella pyrenoidosa, 

 may be a specialised characteristic of this plant, having reference to- 

 its continual occurrence, in nature, in waters which contain a compara- 

 tively large amount of ammonia, notably in sewage and sewage- 

 polluted waters. It is, however, impossible to express a definite 

 opinion upon this point until the nitrogen assimilation of a series of 

 many other plants has been studied in a similar manner. 



DESCRIPTION OF PLATE 8. 



Fig. 1. — Culture on nutrient agar (1 niontli). 

 ,, 2. — Culture on glucose nutrient agar (1 month). 



3. — Cells from a culture on nutrient agar of 10 weeks. 

 ,, 4. — Cells from a culture on glucose agar of 3 weeks. 

 ,, 5. — Cells dividing, f uoni a culture on nutrient agar of 10 weeks. 



