CHAP. II.] MADEIRA TO THE COAST OF BRAZIL. 81 



beautiful little transparent Craiichia — a cuttle-fish not more 

 than a centimetre in length ; a Phillirrhde, scattered over with 

 golden spots ; and an oceanic Planarian. 



As we passed southward the character of the phosphorescence 

 changed somewhat. Pyrosoma and the larger phosphorescent 

 creatures became less abundant, and the light given out by the 

 water, although, on the whole, even more vivid than before, was 

 more diffused, so that water shaken in a vase gave out the uni- 

 form soft light of a ground-glass globe illuminated from within 

 bj a white flame. Even when examined in small quantity in 

 a tumbler the water was slightly turbid, and when the light 

 was properly adjusted, it was seen to contain a multitude of 

 minute trans]3arent bodies, which give out in the dark a clear 

 white light, becoming very vivid, almost a spark, when they are 

 shaken or irritated. 



The largest of these are spherical, nearly a millimetre in di- 

 ameter. They consist of a delicate external pellicle, so thin 

 that it can scarcely be defined under the microscope, but appar- 

 ently siliceous, for, when the little globe is pressed with extreme 

 delicacy between the finger and thumb, the wall of the cell is 

 felt to break like an infinitely thin wall of glass. When the 

 sphere is shaken from the towing-net, it usually contains only a 

 clear transparent liquid, wnth a small irregularly outlined mass 

 of yellowish-brown sarcode sticking apparently against the in- 

 side of the cell-wall. If it be left at rest for a time in sea- 

 water, the sarcode begins to send out prolongations which grad- 

 ully spread in a net-work of anastomosing streams over the in- 

 side of the wall, and in these streams the peculiar and extremely 

 characteristic flowing movement of living protoplasm may be 

 observed, each stream bearing along with it oil-globules and mi- 

 nute granules, as in the well-known " cyclosis " within the cells 

 of the moniliform hairs in the flower of Tradescantia. Under 

 a high power the protoplasm is seen to consist of a clear viscid 

 liquid, moving along with a defined edge separating it from the 



II.— 6 



