1870.] Botany. 525 



wood, and from which the new wood is formed. He finds it not 

 only in the leaves, but in all foliar or "appendicular" organs, 

 normal or modified, as for instance the flowers, but occupying a 

 different position to the cambium layer, namely, between the tissue 

 of the organ itself and the epidermis. The knowledge of this fact 

 M. Cave applies to determine a morphological question which is 

 often a matter of controversy, whether a particular organ belongs 

 to the axis, to the foliage, or to both sets of organs combined ; and 

 he shows that if the formative layer is exterior to the fibro- vascular 

 system, the organ belongs to the leaves ; if interior to it, to the stem. 

 The application of this test proves that the receptacle-like peri- 

 gynous calyx of many plants is a dependency of the axis ; while 

 the pericarp of superior fruits is always formed of metamorphosed 

 leaves and nothing else ; this is also the case with the axile and 

 parietal placentae ; but the free central placenta, as in the case of 

 Primulacese, is a prolongation of the axis. Fruits proceeding from 

 an inferior ovary are composed of two parts, varying in their mutual 

 proportion in different plants, a receptacle-like calyx and carpellary 

 leaves. It is noteworthy that M. Cave found this formative layer 

 to occupy the same position in the leaves and fruits of endogens as 

 in those of exogens. 



Changes in the Colour of Flowers produced by Ammonia. — 

 M. Yogel has recently published the results of some experiments 

 on the changes produced by ammonia in some vegetable colours, 

 especially those of flowers, which he thinks may be of practical 

 importance in the manufacture of vegetable colouring matters of a 

 character similar to the aniline dyes. The colouring matter he 

 states to be of two kinds, united with a different degree of persist- 

 ence to the tissue of the flower itself, and requiring a shorter or 

 longer time to produce any alteration. The change produced in 

 the colour of some flowers, as the rose and phlox, by the fumes of 

 tobacco, is entirely due to its ammoniacal element. M. Yogel 

 found that some colours are altogether unchanged by lengthened 

 exposure to ammonia ; as, for instance, yellows, all reds (except in 

 the case of the Zinnia, which is converted into a brown-red), and 

 dark violets. Blue is sometimes unaltered, sometimes changed into 

 a dirty green and then bleached. In some cases, not only the 

 colour but the tissue of the flower is destroyed. The changes are 

 generally the same as those that take place during the withering 

 of the flower. 



Electricity in Plant Life. — A writer in the 'Gardener's 

 Chronicle ' points out the important part played by electricity in 

 the phenomena of vegetable life. He states that every hair and 

 sharp point in the vegetable kingdom is necessarily a conductor of 

 electricity, which must always be present wherever water rises in 

 the form of vapour. Hence all the young and growing parts of 



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