round the Shores of the Island of Bombay. 261 



and the large cilium floating behind. Capsule slightly tabu- 

 lated over the anterior or conical half, smooth over the pos- 

 terior or round half, which also bears a short sheath in its 

 groove for the long cilium. Length 5 to 8-5600ths of an 

 inch. 

 Found in salt-water pools, and in the sea on the shores of the 

 island of Bombay. 



What, then, accounts for the red colour of the sea and salt in 

 the salt-pans at Bombay may account for the red colour in the 

 sea- water of other parts, although the animalcules may not be 

 the same, — viz. the formation of red oil in their interior. It is 

 interesting, however, to find Darwin^s description of the animal- 

 cule which he found to colour the sea red, a degree south of 

 Valparaiso*, accord exactly with that of Peridiniuniy as may be 

 seen by comparing our descriptions ; while it is not less so to 

 find Saltf stating that the animalcules which produced the red 

 colour in the Red Sea (15°N.) during the day, became luminous 

 and threw out sparks by agitation after dark ; because most of 

 Ehrenberg's marine Peridincea are phosphorescent. In further 

 confirmation of which, Olafsen and Povelsen's statement may be 

 adduced respecting the red colour of the sea on the shores of 

 Iceland, viz. that in 1649, in several gulfs, "the night before, 

 the sea appeared all on fire, and the day following as red as 

 blood/' But it is not necessary for me to cite here all the ob- 

 servations in M. Dareste's ' Memoire' in favour of the red colour 

 of the sea being in many instances owing to the presence of 

 Peridincea, or the white colour to the same animalcules ; suffice 

 it to state that there are many. 



With the explanation of the red colour, then, we have that of 

 the white, which is only seen at night, and appears to be pro- 

 duced by phosphorescence generated in the midst of the oil- 

 globules, becoming less and less powerful probably as the 

 Peridinium becomes redder and more nearly approaches to the 

 fixed or Protococcus-form. I do not of course allude here to the 

 colour of what is termed ^ whale- water,' or to the accumulation 

 of any molluscous animals that can be seen with the naked eye, 

 but exclusively to the colour of water produced by animalcules, 

 which also must again be distinguished from those that are 

 feeding on them, for where the former abound the latter are 

 also sure to be present. Here I have to express my regret that 

 I allowed the red water under consideration to pass away before 

 I thought of ascertaining if the Peridinium which coloured it 

 was also phosphorescent. 



Again, the yellow colour may be produced by the chlorophyll 



* Journal on board H.M.S. * Beagle,' p. 1/. 

 t Voyage to Abyssinia, p. 11)5. 



