HARDWICKE'S SCIENCE-GOSSIF. 



91 



This is what R. N. Worth docs in his "Guide to 

 .'S. Devon," same series as "Kent," published by 

 Stanford & Co. ; they are very good practical guides. 

 I do not know whether the London Flora would 

 include Kent ; I should think it would embrace the 

 borderland. You may find the following useful : — 

 Eentham's "Flora," revised by J. D. Hooker, last 

 edition, 18S7, \Os. 6d. ; Crespigny (C. de E.), "A 

 New London Flora," 1S77, 5^-. I do not know of a 

 later edition of this, nor do I knoM' publishers' 

 names. Any bookseller would order them, or you 

 could get them cheaper by writing to Mr. W. 

 Collins, Scientific Bookseller, 157, Great Portland 

 Street, London, W., or to Mr. W. Wesley, Scientific 

 Bookseller, 28, Essex Street, Strand, London, W.C., 

 both of whom I can recommend; Hooker (J. D.), 

 ■" Student's Flora of British Isles," Macmillan & Co., 

 London, 105. 6d, A revised edition of the above 

 was, I believe, published about 1887. — F. Leigh. 



The Variations of Colours in Plants. — It 

 inay be interesting to readers of Science-Gossip to 

 give a few instances of variation in colour of the 

 same species of plants which have come under my 

 notice. Some flowers are more various in colour 

 than others. For instance, the common wild gera- 

 nium may be found of a dark red, and light red of 

 ^'arious shades, and is sometimes so pale as to appear 

 almost white. The purple orchis of our meadows 

 are of a very dark purple, others of a lighter hue, 

 and some of a very pale red colour, while others may 

 be found of a pure white colour. The flowers 

 amongst which we find most examples are those of a 

 blue, red, and purple colour. Among blue flowers 

 I have noticed the following variations in colour. 

 The selfheal is generally of a dark blue colour, but 

 many flowers are lilac, though some may very often 

 be found of a pure white ; and the sweet violet and 

 milkwort may often be seen of a blue, red, and 

 white colour, and now and again a white specimen 

 of the pretty little harebell may be gathered, but the 

 •colour is not a common one among them. We have 

 more instances of variation in red and purple flowers 

 than in any other colour, and I think I shall not be 

 .far wrong in stating that there are more examples in 

 the two mentioned colours than in all others put 

 together. The red campion, which is dark red, 

 may be found of a very pale red colour, or almost 

 •white. The common knapweed changes in colour, 

 and may sometimes be found white, while red clover 

 may be seen of similar colours. Rest harrow is as 

 •various in the red colour as those just named, and is 

 frequently white. The scarlet poppy and scarlet 

 pimpernel, two flowers of our cornfields, though of 

 so dark a colour, are often light red or even pink. 

 The little field madder and field knautia may be 

 found of various red colours, while white specimens 

 ■of the purple foxglove and heather are of common 

 occurrence. The lesser convolvulus is white and 



rose colour, the wood anemone is sometimes rose- 

 coloured, and the common yarrow is occasionally 

 red, while the common daisy of our meadows is often 

 fringed with red. The pretty yellow flowers of the 

 bird's-foot trefoil have often a mixture of red, and 

 some are entirely red, while the wild pansy of our 

 cornfields may be found of various colours. — H. G. 

 Ward. 



CuLORorHYLL AXD LiGHT.— At least a brace of 

 topics have been recently discussed in Science-Gossip 

 that challenge a more than passing comment. One 

 is the formation of chlorophyll in plants. It seems to 

 be allowed by all the big botanical authorities that 

 there are exceptions to the law that light is an indis- 

 pensable condition for its formation. The germina- 

 ting seeds of many coniferas, and the fronds of ferns, 

 for example, become green even in absolute darkness 

 when the temperature is sufficiently high, and a bright 

 green moss has been fished up out of the Lake of 

 Geneva from a depth of two hundred feet. But let 

 us take care that there be no mistake here. Are we 

 quite sure that in every instance where a suit of green 

 is worn by a plant fabric that the colour is due to 

 chlorophyll ? If we have got any decent sort of eye 

 for colour at all, and endeavour to match the tint of 

 a green gooseberry, for instance, with that of a beech 

 leaf, shall we be satisfied ? I fancy not ; and where- 

 fore ? Simply because the colouring matter in the 

 one case is not the same as that in the other. By 

 personal experiment, I have become convinced that 

 green elderberries and even the seed cases of the 

 sycamore contain no chlorophyll ; and I suspect that 

 the green cotyledons found inside the melons and 

 likewise that of the lemon, recorded in this journal, 

 contain none either. But how can you tell that ? 

 what do you know about it ? Well, I must appeal to 

 the evidence of that most scientific of all instruments, 

 viz., the spectroscope. An alcoholic solution of the 

 substance in question, a small spectro, the use of an 

 eye and a little brains, and the trick is done, the 

 matter is decided. By reference to a back number of 

 SciENCE-GossiP we learn that a very thin layer of 

 chlorophyll is sufficient to absorb all the orange, blue, 

 and violet rays contained in the incident light ; hence 

 the spectrum ought to show very decided dark absorp- 

 tion bands in the portions thereof occupied by these 

 rays respectively when white light is transmitted 

 through a prism. When, therefore, an alcoholic 

 tincture of, say, grass leaves is presented to the slit 

 of the spectroscope, a very dark, broad, clearly out- 

 lined band is seen in the orange next the red, and the 

 whole of the blue-violet portion is blotted out ; 

 sometimes two or three other fainter bands are also 

 seen in the yellow and the green, but these are not 

 characteristic as the former are. So far as I am 

 aware, there is no distinctive chemical test for 

 chlorophyll ; as it is highly probable that it is not 

 invariably of the same chemical composition, nor is 



