330 SECTIONAL TRANSACTIONS.— C, D. 



suitable datum line for the subdivision of the upper Carboniferous (with the exception 

 of the uppermost barren coal measures) into two great groups, viz. (1) a lower group, 

 the Lancastrian of Bisat (Lanarkian of Kidston), characterised by massive grits, 

 sandstones, and thin coals ; and (2) the Yorkian of Watts ( Westphalian of Kidston), 

 containing practically all the main productive measures. 



Mr. H. L. Chhibber. — 



(a) The Lamprophyres and Associated Rocks of Mokpalin, Burma. 



(b) The Volcanic Rocks of the Irrawaddy Delta. 



(c) Ancient Metallurgy in Burma. 

 (Taken as read, in the author's absence.) 



Dr. W. F. P. McLintock and Mr. J. Phemister. — Preliminary Note oh a 

 Torsion Balance Survey over the Swynnerton Dyke. 



Dr. Felix Oswald. — A Mud Volcano at Shugo, Western Caucasus. 



SECTION D— ZOOLOGY. 



(Communications on Textiles, received at special sessions, will be found on p. 411.) 



(For references to the publication elsewhere of communications entered in the 

 following list of transactions, see p. 431.) 



Thursday, September 1. 



Presidential Address by Dr. G. P. Bidder on The Ancient History of 

 Sponges and Animals ; followed by Discussion. (For Address, see p. 58.) 



Mr. H. W. Hervey.— The Fertility of the Sea. 



The animal life in the sea is ultimately dependent upon the minute plants suspended 

 in the water for its nourishment. Like plants on land, these require a sufficiency of 

 light and of nutrient salts for profuse growth ; the phosphates and nitrates in solution 

 in the sea are at times almost entirely used up by the plants and consequently limit 

 their growth. In general the deep water of the open oceans is rich in these two 

 constituents, but is restrained from coming to the upper layers where plants have 

 light enough to grow owing to the greater density of the deep water. Where however 

 this deep water is brought to the surface by currents, minute plants and animals are 

 abundant. By reflecting the rays of white and yellowish light they give the sea a 

 green hue, whereas the barren areas of the ocean are a deep blue when viewed from 

 above. 



In the waters around our coasts, cooling of the surface in winter causes mixing 

 with the bottom water, and as plant life is sparse during these months owing to lack 

 of light the water becomes rich in phosphates and nitrates mostly from the decay 

 of dead organisms lying on the bottom. In March-April, when the daily sunlight 

 reaches about three hours per day, a rich outburst of diatoms utilises these salts in 

 the water, starting from near the surface and proceeding downwards ; in the late 

 summer a second outburst of plant life occurs, utilising the nitrates and phosphates 

 regenerated from the corpses of the spring and early summer growth of plants and 

 small animals. 



Mr. J. T. Saunders. — Environment and Behaviour. 



This paper deals with changes in the behaviour of certain ciliate protozoa in 

 response to very small changes in the environment. The diurnal vertical movements 

 of Spirostomum in small ponds may be maintained indefinitely in aquaria if the bottom 



