UEPORT OF THE COUNCIL. 649 



General Work at the Plymouth Laboratory. 



The two numbers of the Journal issued during the year (Vol. x., Nos. 

 2 and 3) contain several important reports upon investigations carried 

 out in the Laboratory. Mr. K. S. Clark's report on the Larval and Post- 

 Larval Teleosteans in Plymouth waters records the results of work which 

 has been in progress for some years, and Mr. Clark has been able to describe 

 from the material collected by the Association many interesting stages in 

 the life-histories of fishes belonging to a number of different famihes. 

 Some of these stages are illustrated for the first time by careful drawings, 

 which were made by the iVssistant Naturalist, Mr. E. Ford. Incidentally 

 the records of occurrence of the larval fishes give useful indications as 

 to the time and duration of the spawning season of many different 

 species of fishes in the western part of the English Channel. 



A paper by the Director on the culture of the plankton diatom Thalas- 

 siosira gravida in artificial sea-water gives an account of a series of 

 experiments made with a view to studying the exact conditions most 

 favourable to the growth of such organisms, which, as is w^ell known, 

 form one of the fimdamental sources of the food-supply of the sea, the 

 first step of the food-chain leading from inorganic substances, through the 

 invertebrate animals of the plankton and the bottom fauna to the 

 fishes. Dr. Allen has been able to show that good cultures cannot be 

 obtained in a purely artificial medium made by dissolving pure chemicals 

 in doubly distilled water in the proportions in which the salts occur in 

 sea- water with the addition of nitrates, phosphates and iron. If, however, 

 a small percentage of natural sea-water, even as little as 1 per cent, be 

 added and the solution sterilized, excellent cultures result after inocula- 

 tion vdih the diatom. The result appears to be due to some specific sub- 

 stance present in minute quantity in the natural sea-water which acts 

 as a growth stimulant. The actual nature of this substance has, how- 

 ever, not yet been determined. Provided the small quantity of natural 

 sea-water be present in the culture medium the other constituents can 

 be varied within wide limits and the salinity of the medium can also be 

 considerably altered without damaging the growth. 



The Council particularly desires to draw the attention of the members 

 of the Association to the high scientific value and general interest of 

 this paper. Dr. Allen's results are somewhat analogous to discoveries 

 made in the department of human physiology, which suggest that it is 

 necessary to the life of the higher animals that there should be present 

 in their food small quantities of obscure chemical substances which 

 have been given the name of vitamines. 



NEW SEUIES— VOL. X. XO. 4. MAY, 1915. 2 T 



