Re'ports & Proceedings — Britisli Association. 471 



Recent investigations in genetics in general give support to the factorial 

 hypothesis, namely, that the characteristics of the body are represented in 

 the germ plasm, in all probability in association with the chromosomes. 

 Supporting evidence is forthcoming from sex, crossing-over and localisation. 

 Any hereditary change in an organism jnust therefore be associated with 

 factorial change in the germ plasm. Casual mutations readily admit of 

 Mendelian interpretation, but evolution in general does not take place by 

 changes of this kind. Evolution of species often seems to call for a similar 

 change in the whole assemblage of individuals within an area, while 

 palaeontology and the study of numbers of related forms call for gradual 

 successional changes in the same direction as regards any particular structure 

 (orthogenesis) . Mendelian experiments do not yet afford any great support 

 for either of these demands. Observed mutational changes do not call for 

 environmental influence, and are wholly apart from any adaptive con- 

 siderations ; natural selection plays no part in the origin or preservation 

 of variations, but may be eliminative. It is highly questionable whether 

 somatic or environmental influences can modify the germinal factors in 

 definite directions, but disruptive changes and gradual loss of factorial 

 vigour, or perhaps senility, may be contemplated, continued over long 

 ages. As the common germ plasm of a race may at any one time be 

 presumed to be in somewhat the same condition, evolutionary changes on 

 somewhat similar lines may be expected. 



Professor A. Dendy, F.R.S. 



6. Dr. T. Franklin Sibly : The Old Red Sandstone of the 

 Mitcheldean District, Gloucestershire. 



Mitcheldean lies on the Gloucestershire-Herefordshire border 10 miles 

 west of Gloucester, and in the latitude of the Breconshire Beacons. In 

 this neighbourhood persistent westerly dips determine an outcrop of 

 the whole of the Old Red Sandstone, v/ith a thickness of some 

 7,500 feet, in a band scarcely 2 miles wide, bounded on the east by the 

 Silurian strata of the May Hill anticline and on the west by the Carboni- 

 ferous of the Forest of Dean coal-basin. The sequence of strata determined 

 in this locality offers a possible key to the wilderness of Old Red Sandstone 

 in Herefordshire. 



7. Professor W. M. Flinders Petrie, F.R.S. : The Continuance 

 ■of Life on the Earth. 



If by any process of aggregation the earth has been at a red heat, all the 

 lime and soda would be coinbined with the silica (now sandstone) and all 

 the carbonic and hydrochloric acids would be in the atmosphere (now 

 locked up in limestone and salt). The changes from that condition would 

 consist in the acids gradually decomposing the silicates ; at present 

 there is only a minute fraction of the original carbonic acid left in the 

 atmosphere. The decomposition of a few more inches of silicates over the 

 globe will exhaust the carbonic acid, and life could not exist. This may 

 take place in a few hundred thousand years, and such is the limit to 

 vegetable and therefore to animal life, irrespective of solar cooling. The 

 amount of carbon in the strata is probably enough to combine with all the 

 oxygen of the air ; hence, land -breathing animals were impossible until 

 after the carbon had become separated and left oxygen free. This agrees 

 with the aiDpearance of air breathers after the Carboniferous age. 



8. Dr. A. E. Trueman : The Liassic Rocks of Somersetshire 

 and their Correlation. 



The Liassic rocks of Somerset are thin but richly fossiliferous, yielding 

 many large Ammonites. When followed towards the Mendips there is 

 considerable reduction in thickness and marked lithological change. At 

 several localities a white limestone resembling the Sutton Stone of 

 Glamorgan is seen to rest on the Carboniferous Limestone ; it is developed 



