ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 77 



Influence of Annual Temperature on Change of Colour in 

 Leaves.* — According to H. Hofmann, if a thermometer be freely 

 exposed to sunlight, and the readings above 0° 0. added together from 

 the 1st of January to the day in autumn when the turn of the leaf is 

 general, and the same practice pursued for several years, a curve can 

 be constructed which will show considerable variations. If then 

 another curve is constructed below it, composed of the various days 

 on which the change of colour became general, there will be found a 

 correspondence which cannot be accidental, but which, on the con- 

 trary, has been confirmed by so many observations, that the author 

 does not hesitate to formulate it as the expression of a law. The 

 temperatures of January and February, the time of rest for plants, 

 cannot exercise any influence, neither is it probable that of April or 

 May does so, when the leaves first appear, and as there is no regular 

 interval of time between the budding of the leaves and their turn, the 

 few weeks immediately previous to that period are the most important. 

 The more cloudy the autumn, and the lower the sum of the temperature 

 of the last month of it, the longer the leaves remain green. The 

 author draws attention to similar results to be observed with plants 

 grown in shade, although their behaviour under such conditions is 

 not so regular. 



Variation with Altitude of the Colouring Matters of Flowers, f 

 — The modifications produced in the colour of flowers with varying 

 altitude has been made a subject of observation by M. G. Bonnier 

 during a recent tour in Austria and Hungary. To compare the colours 

 he had recourse to a chromometer, by which variations may be detected 

 which it is impossible to observe by simple inspection. The varia- 

 tions, indeed, are generally less intense, in the present case, than 

 those corresponding to different latitudes which are very striking. 

 In a large number of species, a comparison of the tints at two, three, 

 four, and sometimes five different altitudes, showed, beyond doubt, 

 an increase of colour with altitude. This was very pronounced in 

 Myosotis sylvatica, Campanula rotundifolia, Banunculus sylvaticus, and 

 Galium cruciatum ; and, on the contrary, weak in Thymus serpyllum 

 and Geranium sylvaiicum. In ascending, the rose-colour is frequently 

 found to appear in the usually white or slightly coloured flowers of 

 Bellidiastrum Michelii, Bellis perennis, &c. Microscopical examina- 

 tion on the spot, in many cases, proved that the increase of tint is 

 not due to change in distribution of the colouring matters, but that 

 it is the increase of the number of pigment-grains for a given surface, 

 or a more pronounced tint of the coloured liquid in the cells, that gives 

 the more intense colour. The phenomena are connected by the author 

 with the increase of solar radiation with altitude, the atmosphere 

 becoming less dense, and the quantity of aqueous vapour being less. 



Breathing of Plants and Animals. J — Mr. J. Jamieson, in a memoir 

 s\ibmitted to the Royal Society of Victoria, traces certain resem- 



* Journ. Chem. Soc. (Abstr.), xxxviii. (1880) pp. 910-11. 

 f Bull. Soc. Bot. France, xxvii. (1880) pp. 103-5. 'La Nature,' 1880. See 

 Engl. Mech., xxxii. (1880) p. 396. 



t Journ. Ohem. Soc. (Abstr.), xxxviii. (1880) p. 911. 



