96 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



instead. May not these pigments therefore convey more oxygen and 

 so increase the respiratory power by means of the sugar, and so aid 

 a low vitaHty? The mean temperature is low, and as respiration is 

 increased by heat, so this may be a means of increasing it in lieu of 

 sufficient warmth. It is worthy of note that the green colour of chloro- 

 phyll fails to appear if the temperature be insufficient. If any plant, 

 say a blue-bell, be dug up having the lower part of the leaves yellow, 

 and planted again, though now exposed to the light, they will not turn 

 green as long as the weather remains cold. 



Similarly, many leafless plants, as broomrapes, dodder, and other 

 parasites or saprophytes, including fungi, are white or oftener more 

 or less coloured, and are aided by respiratory chromogenes. It has 

 been found that Orohanche Teucrii in full bloom used up its own volume 

 of oxygen in thirty-six hours, i.e. 4"2 c.cm. to each gram of substance, 

 corresponding to a loss of 2'26 mgr. of carbon.'^ 



It is well known that the loss of CO2 by respiration, with the corre- 

 sponding rise in temperature, occurs especially in flowers. May not, 

 therefore, the prevailing yellow colour of the anthers and pollen in 

 Gymnosperms, the earliest flowering plants, and subsequently in 

 Angiosperms, be connected with this object? 



Not being green, flowers might be called parasites on the plant, and 

 that is perhaps Nature's method of supplying the pollen with oxygen for 

 energy to carry on the processes of nuclear divisions within the grain. 

 So, too, chromogenes would supply the means for respiration during 

 the process of growth and development of the petals, but ceases as 

 soon as fertilization has been secured. These are at present merely 

 speculative and hypothetical questions for futurity to answer. 



It must be borne in mind that it is not the carbohydrates which 

 respire, but the living protoplasm, but this loses nothing. The proto- 

 plasm begi]^ the work of respiring, but the decomposition of starch, 

 &c., is done by this living material. 



Sachs had long ago observed of the red colouring matters that 

 " they give remarkable spectra with one absorption band. Some are 

 connected with albuminous substances in much the same manner as the 

 haemoglobin of blood, being like it decomposed at exactly the same 

 temperature as that at which albumen coagulated. . . . They are 

 especially characteristic of red Algse."! 



There is yet another result accruing from respiration, and that is 

 the phosphorescent-like illumination of the mycelia of certain fungi. 

 It has been noticed that Agaricus olearius in the phosphorescent con- 

 dition forms much more carbon dioxide than when it is not luminous. 

 But as respiration is reduced when the temperature is lowered, it has 

 been found that the phosphorescence is very quickly lost. It disappears 

 at 35° or 36° F. The maximum temperature reached was 46O-50° ¥.1 



There remains one more illustration of the use of the spectroscope in 

 the study of plant life. Heliotropism, or rather phototropism, is the 



* Sachs' Physiology, p. 399. f Text-hooh oj Botany, 2nd edit. p. 766. 

 X Sachs' Vegetable Physiology, p. 407. 



