703 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Another fact was observed, that when plants had been kept submerged 

 for some months they started to produce the air type of foliage. " It 

 would seem as if some of the plants after a time became accustomed to 

 the stimulus and refused to respond. Or it may be that, as only the air 

 form is capable of fruiting, in the effort to produce flowers the plant 

 has the ability of self-adjustment to its conditions and develops the air 

 form in spite of its environment." — G. II. 



Protoplasm. 



Protoplasmic Continuity (Beih. Bot. Cent. bd. xii. ht. 3, p. 848, 

 plates 10 and 11). — F. G. Kohl (Marburg) describes and figures proto- 

 plasmic connections in various algne (Chcetopeltis), in Fern prothallia, in 

 the leaf of Mosses, and in the guard-cells of the stomata. A critical 

 discussion of the observations of others is also included in his paper. 



G. F. S.-E. 



Red Spider. 



Red Spider, Biology of. By R. V. Hanstein (Zeit. f. Pfianz. xii. 

 1902 ; pp. 1-7). — Two species of red spinning mite or spider are dis- 

 tinguished : (1) Tctranychus telariu.s, the mite so common on the Lime 

 tree, is green or greenish-yellow, with one pair of red eye-spots, and 

 orange in the winter condition. (2) T. Altkcea (on Hollyhock, Hop, 

 French Bean, &c.) is greenish-brown, slightly larger than the other, with 

 two pairs of eye-spots, and the female is red in colour from August till the 

 following spring. The Lime mite causes the leaves to shrivel and fall, 

 while the webs spun all over the tree are unsightly. The damage does 

 not seem to injure the trees much, as the author has observed them badly 

 attacked several years, yet each spring they produced healthy new foliage 

 and, later, fruit. The Hop red mite, according to Miss Ormerod and 

 other observers, is more destructive ; the author has never found this 

 species on the Lime. Eggs of the Lime mite were seen from May to 

 November. After five or six days, six-legged larvae hatch out, and these 

 after three feeding periods and three resting periods, each from one to 

 two days' duration, become the eight-legged adult. During each resting 

 period the structure is altered. From deposition of the eggs to the 

 mature egg-laying female the life-history is completed in fourteen to 

 eighteen days, so that four or five generations may be produced in a 

 season. Towards autumn, the females change colour, and probably only 

 these survive the winter. No males were observed in spring. The winter 

 is passed in clefts of the bark or in the earth beneath. Sheltered by a 

 dead leaf they were observed to have considerable resistance to cold, 

 although it is probable that many perish in winter. Dry seasons favour 

 their increase, but it was found that a certain degree of moisture was 

 necessary for vigorous growth. Prevention : The author does not appear 

 to have tried remedies himself, but discusses various methods which are 

 much the same as given by Miss Ormerod (Manual of Injurious Insects). 

 The ladvbird and other larva? are natural enemies of the red mites. 



W. G. S. 



An atom y of Khamnace.e. 

 Rhamnaceae, Leaf-anatomy of (Beih, Bot. Cent. bd. xii. ht. 3, 

 pp. 851-424; 15 figs.)- Dr« Kurt Gemoll has examined 120 specie3 



