Occupation of a Table at the Zoological Station at Naples.Report of the Committee, consisting of Dr. P. L. SCLATER, Professor E. RAY LANKESTER, Professor J. COSSAR EWART, Professor M. FOSTER, Mr. A. SEDGWICK, Professor A. M. MARSHALL, and Mr. PERCY SLADEN (Secretary).

I. On the Action of Coloured Light on Assimilation. By CECIL C. DUNCAN. II. On the Function and Correlation of the Pallial Organs of the Opisthobranchiata. By JOHN D. F. GILCHRIST.

THE table at the Naples Zoological Station hired by the British Association has been occupied during the past year, under the sanction of your Committee, by Mr. Cecil C. Duncan and Mr. John D. F. Gilchrist. The object of Mr. Duncan's research was to investigate the action of coloured light on assimilation in marine algae, and that of Mr. Gilchrist's the function and correlation of the pallial organs of the Opisthobranchiata. The reports furnished by both these gentlemen are appended, and give evidence of much patient work satisfactorily carried out."

The Committee have received two applications for permission to use the table during the ensuing year. The first is from Mr. E. S. Moore, who proposes to investigate the origin of the reproductive elements in various types of fishes, as well as in other marine organisms; and the second is from Mr. Edgar J. Allen, who wishes to continue his researches on the development of the decapod crustacea. Each of these applications is for a period of six months, the first to commence at the end of September and the second in April. The occupation of the table for the entire year is thus provided for. Both these gentlemen have already made valuable contributions to our knowledge of the subjects upon which they are engaged, and important results are likely to be obtained from the investigations they propose to carry on at Naples.

Your Committee trust that the Association will sanction the payment of the grant of 100l., as in previous years, for the hire of the table in the Zoological Station at Naples.

Notwithstanding the number of marine zoological stations which have sprung into existence in different parts of the world during the past decade, the Naples Zoological Station steadily continues to extend both in scope and in popularity, and each year shows an increase in the number of naturalists who study in its laboratories: 747 workers have occupied tables from the opening of the Station up to the end of June 1893, 71 names being enumerated on the list for last year.

The Physiological Laboratory, which was built in 1890-91, and forms a handsome addition to the original building, is now thoroughly equipped, and is in full working order. A number of important investigatious have been conducted in this department of the Station during the past year, and doubtless many workers in the wide field of physiology will now be attracted to Naples to avail themselves of the exceptional facilities there offered for carrying out such researches.

The Chemical Laboratory is also a distinct and much appreciated gain to the institution.

The Library, which has always been felt to be an adjunct of incalculable importance to the study and convenience of all who have worked at the Station, is increasing so rapidly that new and more commodious

rooms are now being prepared, capable of accommodating double or treble the present number of books. The Director is unrelenting in his exertions to make the Library as complete as possible, and it is his aim that it should one day rank as the most complete Zoological Library in existence.

The progress of the various publications undertaken by the Station is summarised as follows:

1. Of the 'Fauna und Flora des Golfes von Neapel' the monograph by Dr. Giesbrecht on 'Pelagic Copepoda' (831 pp., 54 plates) has been published; and two other equally large monographs by Professor Della Valle on Gammarini' (about 950 pp. and 60 plates) and by Professor Spengel on Balanoglossus' (about 800 pp. and 30 plates) will appear before the end of the year. Monographs by Dr. W. Müller on 'Ostracoda and by Dr. Jatta on Cephalopoda are ready, and the printing of the former has been commenced. Monographs are being prepared by Dr. Bürger on 'Nemertinea,' by Professor Apáthy on 'Hirudinea,' by Professor Ludwig on 'Echinodermata,' and by Dr. Scheviakoff on 'Foraminifera '; and a botanical monograph by Professor Falkenberg on 'Rhodomelem' is nearly ready.

2. Of the 'Mittheilungen aus der Zoologischen Station zu Neapel,' vol. x., parts iii. and iv., with 18 plates, have been published; and vol. xi., parts i. and ii., with 13 plates, are in the press.

3. Of the Zoologischer Jahresbericht' the whole has been published.

Bericht' for 1892

The details extracted from the general report of the Zoological Station, which have been courteously furnished by the officers, will be found at the end of this report. They embrace lists (1) of the naturalists who have occupied tables since the last report; (2) of the works published during 1892 by naturalists who have worked at the Zoological Station. A list of the specimens sent out by the Station during the past year has also been furnished.

I. Report on the Occupation of the Table. By Mr. CECIL C. DUNCAN.

The algae to be experimented upon were kept in a large tank, with a good stream of water running through, until they had the appearance of being quite healthy. The determination of the composition of the gas given off from the different coloured algae, when subjected to the action of different coloured light, was then proceeded with. The coloured solutions, &c., are as follows:--Diffused daylight; red glass which passed only rays from about B of the solar spectrum to midway between C and D ; yellow light from a saturated solution of bichromate of potash which passed rays from B to about midway between D and E; violet glass passing all the blue and violet and a little red and yellow light; violet light from a strong solution of ammonio-cupric sulphate which absorbed all light up to E, and finally a dilute alcoholic solution of chlorophyll from grass. The gas analyses were made in the gas-room attached to the chemical laboratory, according to Bunsen's method, the CO, being determined by absorption with NaOH and the O, by explosion with hydrogen. The N2 was determined by difference. The same portion of the plant was experimented on with the coloured solutions, &c., mentioned above. Diffused daylight produced the maximum quantity of O2, and only in four out of seventeen cases did coloured light produce more, viz.—

From thirteen experiments with red and yellow light only two experiments with the red produced more O, than the yellow, viz.

2

Diffused light, red and yellow light, all gave larger quantities of O2 than the violet glass. From seven experiments with the ammonio-cupric sulphate solution Sebdenia was the only one to give a larger quantity of O, than produced from the action of yellow light.

Sebdenia, after being exposed to violet light, lost its original colour, and turned a pale green. Several algæ, after having been exposed to the violet light, were killed. The other colours did not destroy so rapidly. From the green light of the chlorophyll solution the quantity of O, found was very small; in one case the total quantity of gas given off was only 0.268 c.c. at 0° C., and 760 mm. mercury.

The next series of experiments were made in order to determine the exact quantity of O, given off from the same plant under different rays of light. A small quantity of the dissolved gases was removed from the sea water by means of a pump. A portion of the plant to be experimented on was placed in an air-tight flask with some of this water. The O2 was determined before and after the experiment by Winkler's method, the difference being the O, given off by the plant under experiment. The results varied considerably, the principal cause being due, I think, to the unhealthy state of some of the algae. After some care the results obtained agreed fairly well with those obtained by the first series of

experiments, Sebdenia, Codium, and also Haliseris giving results very similar to those in the first series of experiments.

On examining the absorption spectrum of the seventeen species of algæ, one is struck by the constant absorption of the extreme red almost up to B, and the strong absorption between B and C which is so characteristic of green chlorophyll. The rays absorbed between B and C are stated by several observers to be the rays most necessary for aiding assimilation. Alcoholic solutions of green and olive algæ had a red fluorescence similar to that exhibited by solutions of green chlorophyll, and if the spectrum from a small spectroscope is projected on to the surface of the solutions of the colouring matter of olive or green algæ, the liquid fluoresces of a dark red colour from about B to some distance in the violet, the red fluorescence being brightest where the greatest absorption takes place in the original alcoholic solution. No fluorescence could be detected in the living plant. A few preliminary experiments were made in order to determine the quality of the light penetrating into the sea, but nothing worth mentioning was observed. I hope to continue these experiments with properly made apparatus.

To the staff of the Station my sincere thanks are due for the great kindness and assistance I have received at their hands.

II. Report on the Occupation of the Table.
By Mr. JOHN D. F. GILCHRIST.

I beg to submit a report of the work done during my occupation of the table of the British Association at the Zoological Station in Naples.

I had for six months been working in the Laboratory of Professor Arnold Lang, on the subject of the pallial organs of the Opisthobranchiata. In order to understand the function and correlation of these different organs, as well as to make use of recent methods of silver and methylen-blue staining and of dissociation, it was necessary to have the animals in the living condition. Accordingly I gladly availed myself of the permission of the British Association to occupy the table at Naples, where alone I could get the necessary abundance and variety of material for such a comparative study. I applied for three months, to begin on April 10; but finding such abundance of material and opportunities for work, I applied for another month, and this was granted.

With the material procured I am fully satisfied. Not only were such forms as Aplysia, Bulla, and Pleurobranchæa to be had in more than abundance, but others, such as Notarchus, Aeera, &c., were plentiful, and other forms which were not procured during my stay, such as Pleurophyllidea and Lobiger, were kindly given me from the stock of preserved material. These, along with the many Nudibranchiata which turned up, put at my disposal abundance of material for a comparative study.

My first endeavour was to thoroughly understand the functional mechanism of the pallial complex, which presents such a variety of

'The band present between C and D in an alcoholic solution of chlorophyll was only to be found in a species of Phyllophora. The very faint band at the junction of the yellow and green in an alcoholic solution of chlorophyll was found in six out of seventeen species, viz., Sebdenia, Vidalia, Peyssonelia, Plocamium, and Ceramium, and very dark in Halymenia. A broad dark absorption band is very constant between b and F, and in only seven species could the violet be said to be absorbed strongly.

interesting modifications in the Opisthobranchiata. This I did by observations on the living animal. Thus, for instance, the mantle of Aplysia was found sometimes to exhibit a motion the effect of which was to keep the water in circulation round the gills. Again, a remarkable process of flaccid skin at the front end of the mantle was found to play an important part in conjugation. I found it also very instructive to ascertain the strength and direction of the current of water in the pallial cavity and elsewhere. Thus in Aplysia depilans and A. punctata the current was much feebler than might have been expected, and in Aplysia limacina it was even more so, while in other forms there was none at all. These and similar facts were noted throughout a variety of forms, and enabled me to deduce some general conclusions-for instance, that the development of the osphradium is in intimate relation with the presence and strength of the current of water, e.g., that in Aplysia depilans, where there is a distinct current, the osphradium is more highly developed than in Aplysia limacina, where the current is markedly less, and that where, as in Pleurobranchæa or Umbrella, there is no current of water passing over the gills, but is drawn directly into them, there is no sign of an osphradium. Again, where, as in Pleurobranchus, the current first passes over the rhinophora, there is no osphradium. This is more markedly the case in the Nudibranchiata, where the place most exposed to the influence of water was found to be the rhinophora. By facts of this nature, and also by a, comparison with the Prosobranchiata, as far as my time would allow, I was confirmed in my belief that there exists a relation of direct proportion between the current of water and the development of the osphradium, there exists a relation of indirect proportion between Osphradium and Rhinophora, and that the Osphradium, whose function has hitherto been regarded as obscure, is to be explained as an ordinary olfactory organ in the same sense as the rhinophora are olfactory organs. To further confirm this I made a series of experiments, but although these seemed to be confirmatory they were not decisive. This difficult physiological work has still to be much further developed.

By direct observation of the living animal I was able to note the details of the contraction of the gills by which the blood is propelled; also to find some renal openings difficult to discover in preserved material. I found also in the remarkable gland before the gills in Pleurobranchæa that there existed a current of water passing over the orifice and down under the gills; also that there was no excretion of mucus on irritation. I was thereby enabled to draw some conclusions as to its function. I found these and similar facts as instructive as the anatomical details I had previously ascertained.

With Golgi's methods I had no more success than others who have tried them on the same animals.

With the methylen-blue method of staining living nerve fibres I at first had also little success, but ultimately succeeded in getting a good colouring by laying the nervous system bare and leaving it for about twelve hours in a weak solution (25 per cent.). Among other things I was enabled by this means to convince myself that no direct connection by means of nerve fibres exists between osphradium and cerebral ganglia, as has been found to be the case in lamellibranchs, though sections cut and coloured in the usual way present an appearance which might be

mistaken for this.

I had considerable trouble in finding a suitable fluid for dissociation,