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JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



that the electric response served as a faithful index of the physiological 

 activity of plants, it would then be possible successfully to attack problems 

 the solution of which at present offers many experimental difficulties." 

 In conclusion the author says : " I have shown that these electric re- 

 sponses are given by all plants and by their different organs. It has also 

 been shown that in the matters of response by negative variation, of 

 fatigue, of modification of response by high and low temperatures, and 

 even in matters of occasional abnormal variations, such as positive re- 

 sponse in a modified tissue, they are strictly correspondent to similar 

 phenomena in muscle and nerve. Judged by the final criterion of the 

 effect produced by anaesthetics and poisons, these electric responses in 

 plants fulfil with animal tissues the test of vital phenomena." — G. S. S. 



Embryology. 



Embryo-sac, Development of, Reduction of Chromosomes, 

 and Fertilisation in Paris quadrifolia, L., and Trillium grandi- 

 fioruin, Salisb. By A. Ernst, of Zurich {Flora, vol. xci. 1902, pp. 1-46, 

 t. i.-vi.).— The embryo-sac here is the lower of two sister-cells, of which 

 the upper disappears ; it is in the division that produces these two that 

 the heterotypic mitosis with chromosome-reduction first appears. The 

 numbers of segments in the vegetative cells are in Paris and Trillium 

 twenty-four and twelve respectively ; the reduced numbers in all subsequent 

 nuclei are twelve and six, the latter being the lowest yet known in 

 flowering plants. A transitory longitudinal splitting of the daughter- 

 chromosomes occurs in the metakinesis of this first division ; and in 

 the remaining mitosis the halving of the chromosomes is homceo- 

 typic (the figures, however, show heterotypic rings) and always longitu- 

 dinal. The antipodal cells have the normal reduced number of 

 chromosomes, and appear to degenerate without multiplying or acquiring 

 nutritive functions. In fertilisation the sperm- and oo-nuclei fuse com- 

 pletely ; while in the pseud 3-fertilisation the second sperm- and polar- 

 nuclei remain distinct till the prophases of their mitosis are advanced. 



31. H. 



Anatomy of Euphokbiace^. 



Euphorbiaceae, Anatomy of. By L. Gaucher {Ann. Sc. Nat. 

 Hot. xv., 1902, pp. 161-309 ; figs. 81).— The results of an investigation 

 on the general and comparative anatomy of 375 species of this order. 

 The author concludes that in spite of the wide distribution of the group 

 and the many variations of external form, there is a collection of anato- 

 mical characters constant enough to define the type Euphorbiacece. The 

 chief characters in the stem are the sib-epidermal origin of the cork, the 

 origin and arrangement of the thickened elements of the cortex and pith, 

 and the distribution and characters of the tannin elements and crystals of 

 calcium oxalate. In the leaf, the characters are the uniform structure of 

 the epidermis and the structure of the stomata. The various types 

 of internal phloem found in the order are described and figured. The 

 latex-system is also specially investigated ; the laticiferous elements are 

 either unicellular or pluricellular in origin, and a table is drawn up to 

 show how modifications of these elements are characteristic of the families 



