RESPIRATION IN THE ROOTS OF SHORE-PLANTS. 327 



2.— RESPIRATION IN THE ROOTS OF SHORE-PLANTS. 



By Dr. J. Bancroft, ike, of Brisbane. 



The following results of <i series of observations on the respira- 

 tion of i:)lants may tend to the better understanding of that 

 function in the bark of trees. (Pis. XIX.-XXVIl!^) 



There is much obscurity on the subject, and as no work, as far 

 as I am aware, supplies any clear account of the matter, I may be 

 pardoned for encroaching on the labours of the botanist proper, 

 by supplying some data that may help future observers in their 

 efforts in elucidating plant respiration. 



I have spoken to Baron von Mueller, of Melbourne, recently as 

 to his views, and am encouraged thereby to bring forward what 

 forms of vegetation have fallen into my hands in Queensland that 

 bear on the subject. 



In the first place, in the year 1881, 1 made various experiments 

 with an organ which grows from the submerged roots of Avicennia 

 officinalis, a tree that is common on the shores of Queensland, 

 extending up the rivers as far as salt water passes. 



This organ, often over a foot long, has not hitherto been 

 described by botanists, and if we turn to the notice of the tree 

 in the " Flora Australiensis,"* no mention of it will be found. 

 My examination of this organ led to the writing of a paper 

 which was sent to the late Professor Balfour, from whom I have 

 a letter of acknowledgment, stating that he was in feeble health 

 and might be unable to do justice to the communication. 



The paper was submitted to the Royal Society of Edinburgh 

 by Professor Dickson, but was not published so far as I am aware. 

 A notice appears of the reading of it in " Natnre."-\ 



Both these botanists having died, I now place the oi'iginal com- 

 munication before you. 



On May 2oth, 1881, being detained by a lady patient, I took a 

 walk on the banks of a salt-water creek botanising. Amongst 

 various things that interested me, a white powder floating on the 

 brackish water, presented itself as an object of inquiry. This 

 powder looked at a distance like the male Vallisyieria flower, but 

 on closer inspection it was observed to issue from openings in the 

 aerial roots of neighbouring yl rtce?zm« ti^ees, the habitat of which 

 is restricted to the muddy banks of salt waters. Some of these 

 upright roots in rapid growth, found casting oft" the white powder, 

 I drew up, together with the horizontal white pithy parts that 



♦Vol. V. 



t Vol. XXV., p. 404. 



