CHAPTER III 



Haematococcus The differences between animals and plants. 



IN striking contrast to Amoeba, which, though primitive, 

 is nevertheless a very typical example of an animal organism, 

 stands Haematococcus or Sphaerella, which, by botanists at any 

 rate, is regarded as a very simply organized member of the 

 vegetable kingdom. Like Amoeba, this organism is of microscopic 

 size, consisting of only a single cell or protoplasmic unit. 



Hcematococcus pluvialis (also known as Spharetta lacustris) 

 occurs in temporary pools of stagnant rain-water or, in the rest- 

 ing condition, in dried-up mud or dust. Though individually 

 invisible, or barely visible, to the naked eye, it may occur in such 

 dense associations as to give the water a bright red (or some- 

 times green) colour and form a red crust on the sides of the 

 vessel in which it is cultivated. A closely related, if not identical, 

 species (Htematococcus nivalis) is the cause of the red patches 

 which are sometimes observed on the snow-fields in Arctic 

 regions. Cultivation is easy, and the same stock may be kept 

 going for many years and multiplied indefinitely. Twenty 

 years ago or more I had a sample given to me in Australia, 

 descendants of which are now flourishing in full vigour in 

 England. It can be dried up when not required and when 

 wanted again in the active condition needs only to be supplied 

 with fresh rain-water and placed in the sun. 



In the resting condition each individual consists of a spherical 

 protoplasmic body (Fig. 5, A) of a bright red or green colour, or 

 sometimes partly green and partly red, with a more or less 

 centrally placed nucleus (mi.). It differs from an Amceba in the 

 presence of a very distinct, firm cell-wall (c-.w.) on the outside, as 

 well as in its definite shape and characteristic colour. The cell- 

 wall is composed of cellulose, one of a group of chemical com- 

 pounds known as carbohydrates. These compounds are all 

 characterized by the fact that they contain only three elements, 

 carbon, hydrogen and oxygen, the hydrogen and oxygen occurring 



