104 J. W. JENKINSON. 



treatment with strong salt solution. The granules are then 

 seen to be the vehicles of the pigment which lies in their 

 peripheral portion^ the centre being colourless (Fig. D, 9). The 

 yellow-green or brown-green pigment seems to be a com- 

 bination of two distinct colouring matters. If the chromato- 

 phores are treated with dilute alcohol they become of a grass- 

 green before they eventually fade ; tliere is thus a brown or 

 yellow pigment, more soluble in alcohol or in water after the 

 death of the organism than the green. In absolute alcohol, 

 however, the yellow-brown pigment is the less soluble. 



By the action of concentrated hydrochloric or sulphuric 

 acid the chroraatophores are coloured bluish green or blue, 

 and by continued treatment with the former hypochlorin 

 masses are diflFerentiated as dark green drops or crystals. 

 These reactions prove that the green colouring matter is 

 identical with, or very nearly related to, the chlorophyll 

 of the higher plants. The yellowish-brown pigment, on 

 the other hand, is probably itself a mixture of two : one of 

 these may be identical, as Geddes supposed, with carotin or 

 xanthophyll, or else with diatomin (phycoxauthin) ; the 

 other may be either the phycophsein of the Phseophyceee, or 

 the phycopyrrhin of the Peridinese. 



These chromatophores are almost certainly not symbiotic 

 Algse, neither a cell-wall nor a nucleus being detectable in them. 



c. The Oil- drops. — These, as above stated, arise by the 

 degeneration of the chromatophores, for when they are formed 

 the number of the chromatophores decreases, and if they be 

 decoloured in alcohol they exhibit traces of the chromatophoric 

 structure. They are at first olive-green, theu red, and finally 

 brown or blackish. They are formed under the influence of 

 direct sunlight, and can be artificially produced by insolation ; 

 if the organism is then removed from the direct light, the 

 shade, which it appears to be the function of these oil-drops to 

 afford, is no longer necessary, and they become disorganised, 

 changing to the brown or black colour. They may, as Geddes 

 observed, be egested and deposited between successive layers of 

 the cysts ; he figures them red, but the present author only 



