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JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



factor in determining the number and significance of the rings of growth, 

 but for the complete interpretation of these a further knowledge of the 

 rate of cambial activity and the independent effect of a hot dry season is 

 necessary. The rate of cambial activity is of special value in determining 

 the varying significance of the xylem differentiations in slow-growing 

 deciduous or quick-growing evergreen trees." — B. I. L. 



Generative Process in Gall Worm. 



Gall Worm, Internal Structure of the. By N. A. Cobb (Agr. 

 Gaz. N. S. W. p. 1031; October 1902).— The article sets forth the 

 examinations carried out on the structure and relationships of the worm 

 causing disease. These proved that the males are possessed of a double 

 internal sexual apparatus. The appearances are often somewhat deceiving, 

 and it would be easy in some cases so to mistake them as to arrive at the 

 conclusion that the internal sexual apparatus is single. As to the internal 

 structure of the testicles little that is new or interesting was observed. 

 The blind end in each organ is occupied by a special cell, and from thence 

 the mother-cells of the spermatozoa extend onward in a single row, or 

 approximately so, throughout the length of the testicle proper. The 

 change by division to spermatozoa occurs near the proximal of the organ. 

 In the seminal receptacle, formed by the junction of the hitherto separate 

 branches of the apparatus, the spermatozoa are arranged in several rows, 

 and the vessel is of such a size as to occupy the greater portion of the 

 lumen of the body near the posterior extremity. The ejaculatory duct 

 appeared to be quite short. Most of these details are carefully set forth in 

 illustrations. — H. 67. C. 



Influence of Light on Germination. 



Germination of Seeds and Light {Beih. Bot. Cent. bd. xiii. ht. 2, 

 pp. 164-172). — Professor E. Heinricher (Innsbruck) has carried on some 

 very interesting experiments on this point. He finds that the seeds of 

 the following plants only germinate in light : Pitcairnia maidifolia, 

 (BromeliacecE) and Drosera capensis. Light favours the germination of 

 seeds of Mescmbryanthemum obliquum and M. pinnatifidum, also those 

 of Echinocactus Grossei, of Echinopsis Bohlandii, and of two species of 

 Dyckia. On the other hand, light appeared to hinder germination in the 

 cases of JEchmea ccerulescens, of Acantliostachys strobilacea, of Stapelia 

 variegata, and of Portulaca oleracea ; the difference appears to depend 

 on the natural habitat of the plant, those of very sunny places or 

 epiphytes being especially favoured by light. — G. F. S.-E. 



Fungicide applied through Root-absorption. 



Lettuce rendered immune against Mildew (Gomp. Bend, cxxxv. 

 No. 23, p. 1007, 1902). — M. E. Marchal has made some very interesting 

 experiments on this subject. He points out the fact that the " downy 

 mildews " or fungi belonging to the Pcronosporaceca are exceedingly 

 sensitive to metallic poisons ; thus the zoospores of the vine mildew, 

 Plasmopora viticola, will not germinate in the presence of i o o o 2 o o o g *° 

 i o (mm) <>f sulphate of copper. Under these conditions, it is asked, 



