26 H^MATOCOCCUS less. 



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

 guished as the anterior extremity, the opposite or blunt 

 end being posterior. So that as compared with Amoeba, 

 Hsematococcus exhibits a differentiation of structure: an 

 anterior and a posterior end can be distinguished, and a 

 part of the protoplasm is differentiated or 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 7t 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 entirely replacing the green, is due to a colouring 

 matter closely allied in its properties to chlorophyll and 

 called h(smatochrome. 



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 structure called a 

 chromatophore (Fig. 3, A, chr), which forms a layer immedi- 

 ately beneath the surface, and in this case is relatively large 

 and urn-shaped. It 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 



