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HARDWICKE'S SCIENCE-GOSSIP. 



some little distance thus. [Schleiden says the 

 tuber returns to its original place in the fourth 

 year.] He was, however, much interested in the 

 remarks about the leaves, and most firmly believes 

 that nothing has been created in vain, and that 

 therefore there must be some reason for the spots. He 

 is accordingly inclined to think that they are the 

 means of conducting from the air some chemical 

 element, which the green colour does not, and he has 

 noticed under the microscope that the cells of a spot 

 are superposed on the green cells, the upper ones 

 being white and purple, and the under ones green. 

 Perhaps they have something to do with elaborating 

 the colour, as in the cuckoo-pint. 



Dr. Simpson, who was kind enough to treat some 

 tubers of 0. mascula which I sent in various ways, 

 has not observed any marked result as regards the 

 spots, but he noticed that one of the plants watered 

 with soft water grew the best. He says that the 

 papers on O. mascula are suggestive and calculated 

 to make one look with more respect on the plant. 



Lastly, there is this piece of additional information, 

 which I am tempted to put down, tremblingly indeed, 

 though it seems more likely than the previous 

 suggestion. I must ask the indulgence of the reader 

 for another theory of the spots. On May 6th, while 

 reading that delightful book, " Freaks and Marvels 

 of Plant Life," I was greatly struck by the facts 

 announced on p. 371, in connection with the tempera- 

 ture of flowers. With their general temperature I am 

 not concerned, except so far as to say that it seems 

 that Dr. Hooker, from observations made in India, 

 has come to the conclusion that the temperature of 

 fluids in a plant coincide with that of the soil at the 

 spot whence the largest absorption is derived ; and the 

 inference is that the liquids, taken up by the roots, 

 being at the degree of heat which the soil possesses at 

 that depth, tend to warm the plant in the cold season, 

 and to cool it (in comparison with the air) in the hot 

 season. Under certain conditions, too, especially 

 during the periods of germination and flowering, 

 great heat is evolved by plants. Oxygen combines 

 with carbon and forms carbonic acid, which is thrown 

 off, and the change or oxidation is accompanied by 

 the evolution of heat ; so that the burning log, the 

 breathing animal, and the germinating plant all 

 exhibit the same phenomenon of carbon in com- 

 bustion. A familiar example of this is the process 

 of " malting " barley. At a subsequent period, also, 

 namely at that of flowering, certain chemical changes 

 take place and much heat is evolved. This is best 

 observed and with most satisfaction when a large 

 number of flowers are associated together, as in the 

 case of plants of the Arum family. Lamarck was the 

 first to observe in 1777, then Senebier in 1800, and 

 Hubert soon after. He found that a thermometer, 

 placed among twelve spadices of Arum cordifolium, 

 registered 142^° when the temperature of the air 

 was 74-75 . 



Now how does this bear on the question of the 

 spots on the leaves of 0. mascula ? Well, if a 

 plant of common arum, which is spotted, evolves so 

 much heat, surely a plant of Orchis mascula, which 

 is much more spotted, must evolve much more heat. 

 It must not be supposed, however, that the spots are 

 the cause of the heat, and I do not mean to convey 

 that impression at all. But, on the contrary, I 

 believe now that the spots are intended to keep the 

 plant cool. For, once more, consider the life 

 history of the plant, and let us take the O. mascula 

 alluded to above. It was found on April 13th with 

 a spike five inches high : by May 23rd the spike was 

 15^ inches high, and a tall perfect steeple of flowers 

 was in bloom, highly scented and most attractive. 



The chemical change and heat must both have 

 been great. The tubers, each 2 J inches X 1^ inches, 

 were exactly two inches below the surface, and the 

 leaves were profusely blotched and blistered through- 

 out their entire length. At the small depth of 

 two inches there would probably be little coolness, 

 but to compensate for this the leaves were blotched and 

 blistered. Why should this be so? "I cannot say for 

 certain as yet, except that the O. mascula will not 

 stand heat ; but if, as I suspect, the shape of the 

 tuber is designed to aid first of all a downward move- 

 ment, and afterwards a return upward movement, 

 then how admirably does this fit in with the plant's 

 requirements ! In the summer the new tuber buries 

 itself, to find an unexhausted position and also to 

 escape the heat, and then, as the roots appear 

 it climbs back, like Horace to his Sabine farm, causa 

 captandi frigus amicum. In February the plant begins 

 to shew leaves, and two months later (in April), 

 when the air is warmer, it flowers. But by this time 

 the leaves are well spotted. I noticed, last April, 

 that the blistering of the leaves in some cases was 

 coincident with the emergence of the spike. Truly 

 this, if correct, is most wonderful, and I hope the 

 wise will ponder it well. Mr. Webster asks if I am 

 not mistaken as to the different depths of the tubers. 

 I must confess that I have not found it so in the case 

 of the experiments I have made, but I have found it 

 so in nature, and I hoped to observe more closely 

 this August, but have been unable to do so. Dr. 

 Simpson is not inclined to accept this cooling 

 theory of the spots, as he considers that the dark 

 colour would have, if any, the opposite effect, 

 for they would absorb more heat than the rest of the 

 leaf. [But are the spots dark ? Hold them up to 

 the light : they are pink. It would be very interest- 

 ing to have them analysed, for thus far I have only 

 been able to test their coolness by Eau de Cologne, 

 the analysis fee being so high.] Dr. Simpson also 

 asks why the O. mascula should want to be kept cool ; 

 the family is one of hot rather than cold climes, and 

 for many years past our summers have surely been 

 cool enough. [But don't the coolest fruits come from 

 the tropics ? Aren't many tropical plants spotted ? 



