322 SECTIONAL TRANSACTIONS.—D. 
The demands of the market are not stable. Without fundamental 
knowledge concerning the inheritance of the various characteristics of the 
lactation it will not be possible to keep pace with market fluctuations by 
simple selection with, or without, the progeny test. 
Finally, productivity depends on close interrelation of control of disease 
with nutrition and genetics. Improved methods of feeding put new stresses 
on the machine, which can only be made by the adjustment of the hereditary 
constitutions of the animals. Experiments conducted by the writer with 
pigs are quoted to show how it is possible for the interior economy of an 
animal to be modified to suit nutritional requirements. 
Dr. A. W. GREENWOOD.—Eggs. 
(1) Selection methods practised along the right lines tend to increase 
productivity particularly in unimproved stock, but progress is slow in 
improved stocks because of the inability of the breeder to control heredity. 
(2) It has been shown that the desirable qualities to select for are inherited 
and their mode of transmission from parent to offspring determined. 
(3) Such knowledge need not necessarily affect selective breeding 
practice because of the present inability to distinguish between hetero- 
and homozygous forms of these genes. 
(4) The application of genetical knowledge to breeding requires either 
a method of distinguishing these forms by their production records, or else 
an accessible technique whereby the genetical constitution of an animal 
may be accurately determined. With this knowledge at his disposal, the 
fixation of desirable characters in a flock can be.easily made. 
(5) The field of work of the geneticist covers not only the mode of trans- 
mission of characters under optimum conditions but also the effect of 
variations in the environment on the resultant expression of gene action. 
For this it is essential to deal with animals of known genetic constitution. 
(6) The final phase in the genetical analysis concerns the relation between 
the gene and the mechanism by which the end result—the character—is 
produced. The possibility of the control of heredity through the control 
of physiological processes is foreshadowed. 
Dr. J. E. Nicuoits.—Wool. 
The interrelations of the fleece attributes differ according to breed, to 
locality, etc. The fleece has to be an adequate covering for the sheep and 
also a saleable product. The wool fibres have usually been considered in 
genetic studies, being the most amenable to analysis among the several 
products of skin metabolism which make up the raw fleece. Studies on 
fineness, length, etc., tend to show that multiple factors are involved, but 
environmental effects are so profound that recognition of the optimal 
states of the various fleece characters, in relation to biological or economic 
conditions, is important. 
In practice, cases are frequently found of selection being most readily 
achieved in specific environments. These are discussed, and attention is 
called to the importance of studying the circumstances which favour selection 
of productive capacities in respect of the main fleece characters. 
Dr. J. L. Lusu. 
Visit to Marine Laboratory of the Fishery Board for Scotland and 
to the Research Station of the Department of Scientific and Industrial 
Research, Torry. 
