TRANSACTIONS OF SECTION K. 579 
the tuber proves the tuber to be hypocotyledonary in origin, while the collet in 
some forms is situated in the cotyledon. 
The anatomical investigation of Conopodium denudatum reveals the remark- 
able fact that root structhre is present throughout the whole of the lower half 
of the ‘petiole’ of the cotyledon, and the same is true of Anemone apennina, 
while in Ranunculus Picaria root structure is only found below the cotyledonary 
node. The plane passing through the two poles of the diarch primary root in 
these forms, also passes through the centre of the first plumular leaf, while 
in their normal dicotyledonous relatives, so far as examined (with the exception of 
one individual of Anemone pulsatilla) the diarch plate is at right angles to this 
plane, as in all diarch forms hitherto described. This is of interest in con- 
nection with the plane of formation of the diarch root in the true mono- 
cotyledons. 
4. On the Systematic Position of Casuarina and its Allies. 
By Emiry M. Berrince, D.Sc., F.L.S. 
Since 1891, when Treub discovered chalazogamy in Casuarina, Engler, 
Wettstein, and other botanists have regarded the Amentifere as primitive 
forms directly descended from certain gymnospermous families. 
The work of many investigators, however, has tended to show that the 
characters on which this view is based are not peculiar to Engler’s class 
‘ Verticillate,’ or even to the Amentiferz generally; and an examination of 
the structure of the inflorescence, flower, and cupule in the Fagacez seems 
to confirm the view, first brought forward by Hallier (but later discarded 
by him), that the ancestors of the Cupulifere were allied to the Rosacee. 
5. Description of some Fossil Fruits. By Brerrua Ress. 
Fossil fruits were found in the shaft of the Langi Logan South Gold Mining 
Company at Ararat. They occurred in an old river deposit at a depth of some 
236 feet from the surface, and were covered by two distinct basaltic lava flows. 
Many of them are of small size, being about one line in their greatest length, 
rounded in outline, and flattened. Each one appears to consist of two carpels, 
and has what may be the remains of a persistent perianth at the base. 
There are also some fruits of a species of Casuarina and some fruits of 
Eucalyptus, and in addition other remains, such as a bud of a Eucalyptus flower, 
and what appears to be a portion of the rachis of an inflorescence of the same 
genus. 
TUESDAY, AUGUST 18. 
1. Joint Discussion with Section D on the Nature and Origin of 
Species. 
The Origin of Species. By Dr. A. B. Renpis, F.R.S. 
Use of the term ‘ species.’—The unit of the systematist who is required to 
catalogue the plants of various parts of the world as they are discovered. The 
‘species’ of the monographer who studies critically an extensive series of 
specimens and recognises ultimate units widely differing in degree from well- 
marked species to subdivisions so critical that it requires an expert in the group 
to appreciate them. 
Each species is eminently adapted to its environment; other than slight 
change of form or of arrangement of parts will tend to throw it out of tune 
with its environment, and therefore prove detrimental. To grow plants under 
alien conditions generally requires care and restriction of competition. The 
theory of descent implies a change in the species, and doubtless also in environ- 
ment, but any change unless very slight or gradual would be detrimental. 
On the theory of mutation species have not arisen gradually as the result 
of selection operating for a long period, but discontinuously by sudden small 
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