540 EEPOET— 1893. 



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 

 algae, 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 charac- 

 teristic 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 alg« 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 algse, 

 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 proiserly made apparatus. 



To the stafi" 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 Opistho- 

 branchiata. In order to understand the function and correlation of these 

 difierent 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 Pleurobranchoia 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 Pleuro- 

 phyllidea 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 Phylloplwra. 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, Tidalia, Peyssonelia,Plocamium, and Ceram'mm, 

 and very dark in Halymenia. A broad dark absorption band is very constant 

 between & and F, and in only seven species could the violet be said to be absorbed 

 strongly. 



