26 H^MATOCOCCUS 



with the flagella went first ; this may therefore be distin- 

 guished as the anterior extremity, the opposite or blunt 

 end being posterior. So that, as compared with Amoeba, 

 Haematococcus exhibits a differentiation of structure : an 

 anterior and a posterior end can be distinguished, and a 

 part of the protoplasm is differentiated set apart as 

 flagella. 



The green colour of the body is due to the presence of a 

 special pigment called chlorophyll, the substance to which 

 the colour of leaves is due. That this is something quite 

 distinct from the protoplasm may be seen by treatment with 

 alcohol, which simply kills and coagulates the protoplasm, 

 but completely dissolves out the chlorophyll producing a 

 clear green solution. The solution, although green by trans- 

 mitted light, is red under a strong reflected light, and is 

 hence fluorescent : when examined through the spectro- 

 scope it has the effect of absorbing the whole of the blue 

 and violet end of the spectrum as well as a part of the red. 

 The red colour which occurs in so many individuals, some- 

 times almost replacing the green, is due to a colouring- 

 matter closely allied in its properties to chlorophyll and 

 called h&matochrome. 



At first sight the chlorophyll appears to be evenly distri- 

 buted over the whole body, but accurate examination under 

 a high power shows it to be lodged in a variable number 

 of irregular structures called chromatophores (Fig. 3, A, 

 chr.\ which together form a layer immediately beneath the 

 surface. Each chromatophore consists of a protoplasmic 

 substance impregnated with chlorophyll. 



After solution of the chlorophyll with alcohol a nucleus 

 (B, nu.) can be made out ; like the nucleus of Amoeba it is 

 stained by iodine, magenta, &c. Other bodies which might 

 easily be mistaken for nuclei are also visible in the living 



