ME. Ii. N. MOBELEY ON FEEYBWATEE ALQB. 321

Various seeds cannot fail to reach the island with these imports ; and the constant importation of hay must have led to. the intro- duction of many more. Shipwrecks furnish additions to the flora occasionally. A vessel laden with grapes was wrecked on the coast a short time ago. The boxes of grapes were washed ashore ; and the grape-seeds germinated in abundance, so that General Lefroy wa8 able to gather a number of small plants for his garden.

[The determinations of the plants alluded to in Mr. Moseley's notes have been made at the Kew Herbarium. The whole collection included about 162 species, of which 71 belong to the Old World. Dr. Rein's list includes 128 species ; and of these at least 53 are amongst those collected by Mr, Moseley.]

111. Notes on Fresh-water Algae obtained at the Boiling Springs at Furnas, St. Michael's, Azores, and their Neighbourhood. By H. N. MOSELEY, M.A., Naturalibt to H.M.S. ' Challenger.'

[Read April 16, 18'74.1

IN the Report of the Circumnavigation Committee, in the section relating to botany, attention is drawn to the fact that Algae are found in hot springs, and observations on such Algae are requested. Whilst staying at St. Michael's, Azores, I visited Furnas with a large party from H.M.S. ' Challenger.' Here there are two sets of boiling springs, in each of which I found abundance of Algae, some of them growing under remarkable conditions.

In the valley of Furnas there are two distinct sets of hot springs-those at the village of Furnas itself, and others at a dis- tance of two or three miles, situate on the shores of the lake of Furnas. I n both places numerous hot and cold mineral springs discharge themselves through openings of various sizes irregu- larly distributed over an area covered with partly ancient, partly modern, geyser-formation or hot-spring deposit.

At the springs near the lake of Furnas the principal spring consists of a large basin 6lled with bluish water, in the centre of which a violent ebullition is always going on. The water in this basin is intensely hot. The stones at the margin are covered with a red incrustation ; but this ap- pears to be entirely minerd. A short distance from this basin

No Algze were found in it.

322 ME. II. N. YOSELEP ON FEESHWATEB ALQE.

and a little further from the lake is a second spring, where from a cleft about a foot wide are discharged steam and hot water toge- ther with large quantities of sulphuretted hydrogen. The hot water is thrown out in rapidly succeeding jerks and splashes, and strikes against the sides of the cleft from which the discharge proceeds. The sides of the cleft, where bathed by these conlrtant splashes of hot water, are covered with a layer of shiny-looking pale yellowish-green matter, with an irregular wavy surface. Some of this layer was cut off with a knife, with considerable dif- ficulty, since the water was so hot as to scald the hands when it splashed them. The layer was about an inch and a half thick. It was tough and elastic, and appeared composed of gelatinous green vegetable matter mingled with a grey earthy deposit disposed in successive layers. The dyied specimen accompanying these notes has, of course, shrunk greatly ; and hence the earthy constituents of the mass are more conspicuous than in the fresh condition. The specimens preserved in h i d preserve their original character well. On looking at the mass in section it is seen that immedi- ately internally to the outer yellowish-green crust is a narrow layer coloured of an intense blue-green (phycocyan); and on ob- serving vertical sections of the mass with the microscope, the Algae composing it are found intensely coloured in this layer and very pale on the outer or exposed layer. It would appear pro- bable that the Oscillatorim are unable to develop their full colour- ingmatter on the outer crust, where it is exposed directly to a solution containing sulphurous acid and various gases, but that they are able to do so a short distance within the mass, where pro- tected, and that here the growth ie most vigorous. Deeper still in the mass the conditions are again less favourable, and the Algae become pale from want of su5cient light &c. Thc mass itself is composed almost entirely of Oscillatorim mingled wrth a Chroo- coccus.* The Chroococcue wa8 not so abundant in the samples of incrusting matter in this hot spring as in those from the spring a t Furnas. Amongst the green matter are a few skeletons of DicE tomama, (a Navicuk) ; but these are very probably derived from a cool spring situate just above the sulphur-spring, the water of which miogles with that of the sulphur-spring, and, indeed, appears

* What Mr. Moseley dWribe8 as Chroococcm is apparently Botryocoecus Braunii, Ktz. (see infrck, p. 328). Mr. Archer detected no true 08cillatWia in the gatherings ; the plant 80 called by Mr. Mboseley is pomibly s To@othria- (me infra, p. 332).

ME. R. N. MOSELEY ON FRESHWATER ALQX. 323

to supply a large share of the water of most of the hot springs, the water being merely heated and impregnated with various mi- nerals $c. by the discharge of steam and various gases from aper- tures in the: several basins into which it finds its way. Very little water flows away from these lake-springs, although the large basin in constant ebullition has the appearance of discharging large volumes of hot water. The small cool spring above referred to contains abundance of Naviclcb and other Diatoms, such as those met with amongst the green matter growing in very hot water. Specimens of these diatoms from this source were pre- served in fluid.

Close by the hot sulphur springs are shallow pools ofhot water, in the bottoms of which are holes of small size from which hot gases are constantly discharged together with some hot water. The bottom and edgings of these pools are of soft greyish mud. All round the edges is a thick brilliant green creamy deposit, which forms a tough cake on drying, and consists entirely of a Chroococczcs. A similar bright green deposit was found coating the interior of some holes on the margin of the pools,from which a constant discharge of intensely hot gas was taking place. The water of the pool itself was SO hot that it was not without diffi- culty that samples of the Algs and water were got into a small bottle. A red incrustation which occurs round some of the fume- role apertures contains no Diatoms or other Algs.

At the other set of hot springs at Furnas is a boiling sulphur spring, much like the one already described, but having its water rather muddy, and forming a transition to the regular mud-spring situate not far off. The walls of the cleft here are, as in the spring near the lake, covered with a thick vegetable deposit, which resembles the other in all respects, except that it contains more Ch~oococcu8, and has a curious honey-combed appearance on the surface. In each case a considerable quantity of the mud or earthy deposit from the water enters into the composition of the incrusting mass.

Immediately below this hot sulphur spring is a sort of swamp of hot mud, with occasional small puddles and various openings discharging hot gases or water, and surrounded by crystals of sulphur &c. In this water, which was too hot to bear the finger, the same chroococc~s as observed at the springs near the lake was abundant, but, as in the former case, unmixed with Oscillatorie. A little lower down in a small pool of hot mud and water, so hot

321 ME. H. N. MOSELEY ON FBEBEWATER ALGZ

that the finger could only be borne in i t for a short time, grows Sedge, specimens of which are forwarded with these notes*, and an abundant growth of Algae, Chroococcus, Oscillatorice, and some Diatoms with endochrome complete.

The Algae mentioned by Rabenhorst as being found growing in warm springs appear to be of similar forms to those found in the Furnas springs ; Rabenhorst gives those of Oscillatorice as living under such conditions. 0. amphibia occurs at Carlsbad in water from 96' to 104' F., 0. elegans in very hot water at the same Ioca- lity ; and 0. graciZlima also occurs in hot springs (Rabenhorst, Flor. Eur. Alg.'- sec. ii. p. 97). Chroococczcs mewbranemis

is further described as occurring with Oscillatorice at C$rlsbad (Rabenhorst, 2 . c. p. 31). I have no works at hand from which to find out whether the Algae form similar crusts in Carlsbad and elsewhere. They evidently grow in much hotter water at the Azores than at any of the German baths ; and it is unfortunate that our party had no thermometer with them registering up to boiling-point, with which to test the actual temperature of the water from which the Algae were gathered.

Hartung (' Die Azoren,' Leipzig, W. Engelmann, 1860, p. 173) gives the general temperature of the springs, after Webster (6 Description of the Island of St. Michael,' W. Webster, Boston, 1821), as from 71' to 206' F., and those of the lake of Furnas as from 78' to 190' F. The water from which the Algae were ga- thered was in the pools from which the Chroococcus was collected, as far as I can now judge, after testing water of successive tem- peratures with my finger, about 14'3' to 158' F. The water in which the sedges grow is from 113" to 122' F. The water of the sulphur-springs, in the area splashed by which the Osn'llatoria we found, is quite scalding to the hand,' and probably between 176' to 194" E. It would be interesting to grow Oscillatorah in some vessel and gradually subject them to higher and higher tern- peratures on a sand-bath to ascertain what amount of heat they would bear.

In a warm stream of about 95' F., trickling over rocks, was found a Conferva growing amongst the fibres of a moss. In a cold iron-spring close to the hot springs at Furnas the

grass-roots and sedges growing in the water are covered with dense ferruginous deposit. This deposit is full of Diatoms.

TI) the lake of Furnas, new its margin, and at the end where * ~ 1 , ~ ~ klange~l to &mws r t c i r f z f lmw~, Spr (t>.ftw p .?.?Q

MR. H. N. YOSELEY ON FRESIIWATER ALOE. 325

the boiling springs are situate, are several patches where hot sulphurous gas is discharged through its water, rising to the sur- face in constant bubbles; and in some of these places small springs of hot water exist. The whole lake is rich in various AlgE ; but these especially flourish around the patches where gas- discharges take place. Specimens of the Alga? are forwarded preserved in fluid. Amongst them are Nostoc, Staurastrum, Oscil- latoria, Rydrodictyon-and many others, of which I failed to deter- mine the genera. Under certain conditions the Algae, mixed with the decaying remains of species’of Potomogeton &c., form a sort of scum on the shore of the lake, which iR left high and dry as the water recedes, and, under the action of the sun, passes into a pe- culiar tough sticky resinous-looking substance of a light brown colour, which may be gathered in pieces of considerable size. The substance has a strong smell of sulphur, and would probably, on analysis, be found to contain a good deal, since much sulphur must be precipitated in the lake-water by the sulphuretted hydro- gen gas constantly discharged through it, and a scum on the sur- face would naturally pick this up. The substance, such as it is, appears to me of interest, since it seems, as far as I can re- member, t o resemble somewhat a peculiar elastic substance, a specimen of which is in the Kew herbarium amongst the lichens, and which is found on the shores of a lake in Australia. There is some doubt as to the origin of this substance; and it has be& held to be a mineral, and Professor Maskelyne has specimens in the British Museum. The substance from the Lagos do Furnas may help to clear up the difficulty. There can be no doubt as to the brigin of the specimens from Furnas. In some cases whole. leaves of phanerogamic plants are included in it. It is perhaps found more developed and thicker at certain seasons. Such it

substance could probably only be formed in volcanic lakes in the presence of peculiar chemical conditions in the water.

Some Algae, Diatoms, &c., were collected in a mountain-stream near Furnas and in some fountains by the road-side. They are remarkably abundant, but apparently of familiar forms.

There had been three months’ drought before our arrival at St. Michael’s ; hence Fungi were very scarce : I met with two only.