B. N. Thomas. 
precipitation with alcohol may be merely the result of attenuation. 
The oxidases of the beet and potato appear to be related to one 
another and to be among the strongest plant oxidases; carrot and 
parsnip oxidases are much weaker ; malt diastase and papain still 
more so, and pepsin has no oxidase reaction other than a weak 
peroxidase reaction with guiacum. Strong metallic poisons will 
arrest the action of organic oxidases or destroy them (apple, potato 
carrot, parsnip) if rapid penetration is assured. Hence the organic 
oxidases are possibly proteids, with or without metals in basic or 
acid combination. I n general, oxidases, whether organic or inorganic, 
may vary from strong to weak. The strong will cause direct oxida¬ 
tion from the oxygen dissolved in a watery solution, the weak will 
transfer oxygen from labile oxygen compounds such as hydrogen 
peroxide, or will use dissolved oxygen in the presence of sensitisers 
such as sodium chloride. It is possible therefore that the sodium 
chloride always present in the ash of plants may not be an entirely 
useless constituent, but may exert a stimulatory or controlling action 
on plant metabolism in connection with special oxidation or in 
respiration in general. 
Joint Discussions, 
The section also met for joint discussions on two occasions. 
In Melbourne, in conjunction with Section D, a discussion was held 
on the Nature and Origin of Species. It was opened by 
Dr. Rendle, who maintained that not sufficient evidence could be 
produced of the existence of the hybrid forms suggested by Lotsy 
to be the source of new species by subsequent segregation. Further, 
Dr. Rendle tests all theories of origin of species by the suitability 
of the new form to its environment, and therefore he is unable to 
support Lotsy’s view, in that there is no suggestion that such new 
forms are more suited to the environment and therefore even if 
produced they are not likely to persist. A similar criticism applies 
to sports, as it is held that marked changes vyould be detrimental 
and therefore exterminated in nature. 
The mutations of de Vries do not appear to differ in kind but 
only in degree from the individual fluctuations which are usually 
non-heritable. It is believed that each species represents the 
resultant of a number of slight individual variations rather than of 
a sudden mutation. 
In Sydney, Sections K, C, D and E held a joint discussion on 
Past and Present Relations of Antarctica in their Geological, 
Biological and Geographical Aspects, in which Professor Seward 
took part. 
