84 Field Naturalists' Club — Proceedings. [^ 



ict. Nat. 

 Vol. XXX. 



be even doubtful if the growths referred to should be called 

 glands at all. He then discussed various functions which they 

 might perform, without professing to arrive at satisfactory proof 

 of any particular function. 



Mr. A. D. Hardy, F.L.S., remarked that he had hstened to the 

 paper with very great interest, but was not disposed to comment 

 as fully as might be expected, in view of the reference to his 

 own paper, as he was at present engaged in observations with 

 experiments which were not yet ready for discussion. However, 

 in passing, one or two matters might be alluded to. With the 

 author, he was in doubt as to the function of the glands, so 

 called, more particularly in the case of Acacia mollissima, of 

 which a number of trees had been under almost constant 

 observation, when no exudation had been seen excepting once, 

 when one spring morning a single small drop ghstening on a 

 gland, and blocking the orifice, was affording breakfast to a 

 small black ant. There was just sufficient clear liquid to be 

 evident to the taste, to which it was quite sweet. He regarded 

 the presence of minute animals in the glandular hollow as being 

 equivalent to rats sheltering in a drain or barrel, or wood-Hce 

 under inverted flower pots, the nibbling of adjacent tissue being 

 a result of environment, and not a cause of selection of such. 

 While agreeing with much that the author had stated, he did 

 not see eye to eye with him on several points, and hoped to have 

 something to place before the Club at an early date. 



Professor A. J. Ewart, D.Sc, congratulated the author on his 

 paper, and said in his opinion it was a philosophical paper with 

 an experimental leaning. He considered the glands to be 

 structures produced by the plant, and not in response to 

 stimulation by insects ; the latter go in because they find there a 

 shelter. The general structure of the glands suggests hydathodes 

 (water-excreting glands), but some points, however, in the 

 structure do not correspond with this theory. Another kind of 

 gland, which is possibly a hydathode, is found on the leaves of 

 the genus Coprosma, and is in the form of a pit beside the vein ; 

 the function of this is even more in doubt. Hydathodes enable 

 the plant to get rid of surplus water, and hence are usually in 

 action at night, and may not function at all during a dry 

 season. There was much that could be said one way or the 

 other, and a good deal of experimental work could still be done. 



The author, in reply, said he did not intend to suggest that 

 insects formed the glands, but that they bred in them. He 

 mentioned that large numbers of Black and Silver Wattles along 

 the Yarra, between Healesville and Launching Place, were being 

 completely destroyed by the larvae of some insect, but of course 

 did not associate these with the insects of the glands. Settlers 

 erroneously considered them to be the Pear Slug. Mr. F. Spry 



