104 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



In dealing with the question of direct infection of the yellowing 

 leaves and the non-infection of the normal green leaves, the author 

 suggests the following possibilities : (1) that some chemotropic substance 

 present in the cells of the yellowing leaf attracts the germ-tubes, whereas 

 no such chemotropic influence is exerted by the normal leaf ; (2) that in 

 the case of non-infection of a normal leaf some substance from the 

 epidermal cells diffuses through the cuticle in sufficient quantity to 

 neutralize the effect of the small amount of poisonous substance secreted by 

 the germ- tubes, whereas no such substance diffuses from the yellowing 

 leaf ; or (3) that the change in the vital activities of the leaf consequent 

 upon yellowing induces some alteration in the composition of the external 

 cell-walls which enables the germ-tubes to penetrate. It is left for future 

 research to decide which of these suggestions is correct. 



With regard to the experiments on the mineral starvation of the host, 

 the results agree with those obtained by Marshal Ward with Puccinia 

 dispersa, viz. that mineral starvation of the host had no appreciable effect 

 upon the infective power of the fungus. — A. D. C. 



Bougainvillea Cypheri. By Aug. Nonin (Bev. Hort., January 1, 

 1909, pp. 12, 13 ; coloured plate). — A very fine form indeed. Flowers 

 (bracts) nearly twice the size of B. glabra Sanderiana shown for 

 comparison. Colour identical, a great improvement. — C. T. D. 



Cabbage and Onion Maggot. By J. B. Smith and E. L. Dicker- 

 son (U.S. Exp. Stn., New Jersey, Bull. 200, February, 1907 ; 12 figures).— 

 In New Jersey great losses have been sustained by growers on account 

 of the attack of these maggots upon the plants. Remedies which are 

 successful in one district unfortunately sometimes are of no avail in 

 others. The insects are described and their life histories given. It is 

 considered that cultural methods of control are of little avail against the 

 onion fly, but of great importance in the case of the cabbage maggot. It 

 is recommended that all cabbage roots should be removed as soon as done 

 with and destroyed ; all cruciferous weeds should be destroyed ; where 

 beds of turnips, &c, have been badly affected, the ground should be ploughed 

 late in the autumn and again early in the spring ; when a crop is found to 

 be badly infested early in its growth it should be dug in deeply ; rubbish 

 heaps should be burnt and outbuildings, &c, cleansed by sulphuring or 

 whitewashing. The time of sowing onions also has some influence on 

 the amount of damage done. Late sowing both in autumn and spring 

 was found to be followed by the best results in New Jersey, as the various 

 broods of flies were then avoided. Quick- acting fertilizers are useful, since 

 they bring the plants rapidly over the season when attack is most to be 

 feared. Cabbages and cauliflowers should be firmly planted, since then 

 the newly hatched larva will be unable to make its way down through 

 the hard soil so as to find a part of the cabbage sufficiently tender for it 

 to attack. Various substances were tried, with varying amounts of 

 success, as preventives, including tarred paper cards placed round the 

 stem of the plants upon the soil, carbolic acid and lime, kerosene and 

 sand, powdered tobacco, powdered white hellebore, dry lime, bran and glue ; 

 and as destructive measures, the application of carbon bisulphide, carbolic- 



