654 
THE VOYAGE OE H.M.S. CHALLENGES. 
and a rush. About the mouths of the cavities from which hot gases were slowly being 
exhaled, a moss was found growing in great abundance, with several lowly organised 
Cryptogams ; the whole being confined to the spot occupied by these fumeroles, and 
forming green patches in the midst of the surrounding entirely bare rock. 
The hot streams were full of green Algae, and as these streams, being very small, 
became cooler and cooler from their source downwards, the temperature at which the 
Algae commenced to flourish could be determined. At the source of one of these streams, 
as it issued from beneath the volcano, the water had a temperature of 145°'2 F., and 
was thus too hot to be borne by the hand. Here there were no Algae at all growing in 
the water. There were, however, small green patches on stones projecting out of the 
bed of the stream into the air, and also along the margins of the stream where they were 
not bathed by the hot water itself, but only soaked up the moisture and received the 
spray occasionally. At a distance of a few yards lower down, in a little side pool fed 
by the stream, abundance of Algae were growing, but the pool had a temperature of only 
101°' 5 F., though the stream which fed it constantly was at 122° F. Lower down again, 
Algae were growing in the middle of the stream, in water at 11 3° ‘5 F., and this seems 
thus to be the limit of temperature at which the particular Algae gathered will flourish 
in water impregnated with a certain amount of salts in solution. No doubt the amount 
of salts present has a limiting effect as well as the temperature. Oscillatoriae have been 
observed growing in water, at a much higher temperature, even 178° to 185° F. 1 The 
fact is interesting, as showing that green algae of some considerable complexity may 
have commenced life on the earth in its early history, before the water on its sur- 
face had anywhere cooled down to a temperature sufficient to be borne by the human 
hand, and which may have been strongly impregnated with various volcanic gases and 
salts. 
The upper slopes of the mountains of Camiguin Island were thickly wooded ; while 
the lower slopes were cleared and planted with Manila hemp. A Manila hemp plantation 
is not at all pleasant or easy to traverse ; the large trees, a species of Banana ( Musa 
textilis), from the stems of which the fibres known as Manila hemp are obtained by 
maceration, are planted close together. The plantations are full of fallen stems in a 
half decayed condition, nasty pasty masses, which block the way and are very un- 
pleasant to handle and climb over, or crawl beneath. 
At 6 p.m. the vessel left the anchorage and steered to the westward towards Silino 
Island. In steering towards, as well as on leaving, the anchorage, the north points of 
Camiguin Island were kept in line, and no soundings were obtained with 1 5 fathoms until 
the Sandy Cay on the reef bore west of north. Whilst the ship was at anchor, the tide was 
falling until 4 p.m., after which it began to rise ; the ebb stream set N.E., the flood S.W. 
1 See W. T. Thiselton Dyer, Proc. Linn. Soc. Lond. (Bot.), vol. xiv. p. 327, 1875. 
