* THE VICTORIAN NATURALIST. 101 



SOME PECULIAR CHANGES IN THE COLOUR OF 

 THE FLOWER OF SWAINSONIA PROCUMBENS. 



By J. P. ECKERT. 



(Read he/ore the Field Naturalists' Club of Victoria, 12th 

 October, iSgi.y 



The Swainsonia procumbens rouses the keen interest of the 

 naturalist in regard to the variability of the occasional changes in 

 the colour of its petals. There are also certainly other plants which 

 undergo a peculiar change of colour in the flower, but in these 

 cases the change is final, i.e , the colour does not return to its 

 prior state, or it is effected by the higher or lower temperature, 

 or the more or less intense action of light together with the 

 chemical action of protoplasm and cellulose. 



For ten years I have during every spring paid special attention 

 to the Swainsonia species, and more so to the change of colour 

 in their petals. When the flower opens the corolla is always 

 lilac (rarely perfectly white, although I found a beautiful specimen 

 of purest white last spring). A day or two after the flower is 

 opened the alteration commences. Why this alteration does not 

 commence immediately after the blossom is out is very difficult to 

 account for ; but I should think that it might be due to particular 

 substances not being yet formed, and whose formation depends 

 upon the action of light and heat. The first change of pigment 

 is noticed in the longitudinal venules of the largest petals. These 

 assume a deep crimson, then at two different points of the 

 petal a dark blue is noticed, which gradually expands to about 

 nine-tenths of the diameter of the whole petal, one-tenth of 

 it — the periphery at the same time decreasing in brifliancy 

 as the other increases — assumes a paler appearance in pro- 

 portion to the other. The variability in the central portion 

 is from deep dark blue through all colours of blue to rose in one 

 and the same individual. Frequently the petal will assume, after 

 having undergone the different changes, its original pigment, i.e., 

 such as it had when it opened, and remain so for some time and 

 then precisely repeat the whole reaction ; but the phenomenon 

 becomes still more striking by the fact that the act of changing 

 the colour appears to come to a standstill for even days — for not 

 the slightest variation either way can be noticed — when suddenly 

 the act, as before described, will be repeated with the utmost 

 precision. As regards the white specimen I mentioned, I had an 

 opportunity to observe that closely too. I visited the plant nearly 

 every day for a month and noticed its peculiarity. Being pure 

 white, it naturally must follow that the metamorphosis (if I am 

 permitted to call it so) was, in appearance, slighdy different, 

 although in its essential parts it was much the sanie. The longi- 

 tudinal venules appeared originally of an extremely transparent 



