SCIENCE AND INDUSTRY. 
produced in the plant by its environment. When the desired heritable variant is 
isolated, selection can do nothing more until nature produces another heritable 
variation. In other words, selection cannot create anything new. It merely 
isolates and preserves any heritable variations produced by nature. These prin- 
ciples were illustrated by the results obtained in the breeding of sugar beets 
and the Illinois. corn-breeding experiments. Hybridization offers unlimited 
opportunity for the production of new types of plants. The Mendelian conception 
of the plant being composed of unit characters based on specific factors trans- 
mitted in accordance with a definite scheme of inheritance is of great service to 
the plant breeder, because his final objective is the production of a type which 
will combine in one variety the greatest number of desirable properties. The 
mode of inheritance of many unit characters has been worked out, but the 
‘inheritance of qualities of economic importance, e.g., yielding capacity, disease 
resistance, milling quality, drought resistance, still remain unsolved. As the 
applications of Mendel’s discovery are extended, it is bound to have a great 
influence on the breeding of plants, for it will ultimately provide the breeder 
with definite knowledge as to the manner in which every unit character of 
practical significance is inherited, and the manner in which the characters may 
be associated and combined for the production of improved types of plants. 
Mr. F. Chapman, A.L.S., exhibited two remarkably well-preserved plant fossils 
in the voleanic tuff of Mount Gambier, from the National Museum collection. 
One is the frond of the common bracken -(Pteridium aquilinum), the other a 
leaf of the silver banksia (B. marginata) still living in the district. It was 
pointed out that the volcanic tuff in which they are enclosed represents the last 
stages of volcanic activity, and that the tuff cones, together with the basal lava 
flows, were partially swallowed up by subsidence similar to that giving rise to 
the caldera of Tower Hill, and since filled up by the water forming the Valley 
and Blue Lakes. The tuff formed a bed 200 feet thick in one part, and the 
volcanic dust drifted 7 miles to the north-east, covering much growing vegetation. 
The occurrence of the ubiquitous bracken shows that it was established long 
before settlement by man. - 
At the December meeting the following papers were read:— 
1. Researches into the Serological Diagnosis of Contagious Pleuro- 
Pneumonia of Cattle. By G. G. Heslop, M.V.Se., D.V.H. (Walter 
nae Eliza Hall Fellow). (Communicated by Professor H. A. Wood? 
ruff.) 
2, New or Little-known Victorian Fossils in the National Museum. Part 
XXV.: Some Silurian Corals. By I. Chapman, ALLS. 
The author describes six new corals, and gives detailed observations on two 
others. . The corals all belong to the Yeringian stage of the silurian. 
3. Contributions to the Flora of Australia. No. 29. By A. J. Ewart, 
D.Se., Ph.D. “ 
This forms No. 29 of the author’s “ Contributions,” which have been published 
from time to time in the proceedings of ‘the Society. Beyeria virgata is a new 
species collected on the Elder Exploring Expedition from the sand hills near 
Lefroy, Western Australia, and was placed for a long time under B. brevifolia, 
from which it is, however, quite distinct. 
4. The Estimation of Acidity. By Dr. J. M. Lewis. (Communicated by 
Professor W. A. Osborne.) ; 
The paper deals with various methods which are in practice available for the 
determination of the hydrogen ion concentration of solutions, i.e, (1) the use 
of a “ladder” of indicators after the manner of Salm and Sorensen, with the 
improvements in method which have more recently been introduced; (2) the 
hydrolysis of esters; and, lastly, and principally, with the electrometrie method. 
The writer deals at length with the theory of “contact potential,” and shows 
how the development of the method is due to the work of such men as Van’t 
Hoff, Nernst, Sérensen, and Wilsmore, to mention some prominent names only. 
The use and construction of the calomel electrode of Ostwald is explained,, 
and the Poggendorff compensation method of measuring the small e.m.f. developed. 
by the system when arranged for an estimation of hydrogen ion concentration is 
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