684 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



vitality of the host-plant, parts being young and delicate. In all cases 

 much more active (parasitic) infection took place when saprophytic 

 nourishment was used as a starter for the conidia. 



When the mycelium penetrates a soft tissue, this becomes darkened, 

 the cells separate with a loss of turgidity, &c, the tissue being affected 

 considerably remote from the filaments, due, according to Ward, to the 

 fact " that these secrete a cellulose-dissolving enzyme which transforms 

 the cell-substances into available food-material for the fungus." 



When a Lettuce-leaf was placed in a watery extract of mycelium, 

 all the tissue in contact with the liquid became softened and discoloured 

 and soon disintegrated, just as in a leaf with the fungus actually growing 

 in the petiole. 



Hence the toxic principle of this fungus is a soluble substance given 

 off by the mycelium. The effects are — first, the death of the cells ; and 

 secondly, the disintegration of their walls and contents. The poisonous 

 substance is not an enzyme ; but the second result is caused by a variety 

 of enzymes, not necessarily always the same, each affecting its particular 

 substance. 



The author then gives results of experiments, which established this 

 last-mentioned conclusion, with some twenty-four vegetable substances, 

 of which sugars and many others were capable of supporting the fungus. 

 The results in each case are described in detail. 



The toxic substance which first kills the cells is probably oxalic acid 

 formed as a by-product. — G. H. 



Calcium-oxalate in Leaves. 



Calcium-oxalate Crystals in Seedling's of Alsike (Trifolium 

 hybrid um). By J. Percival (Joum. Linn. Soc. Bot. vol. xxxv. p. 896, 

 with 5 figures, July 21, 1902). — The author says: "The very definite and 

 characteristic position in which the crystals of calcium-oxalate occur in 

 the leaves of most leguminous plants led me to consider that a detailed 

 study of their first appearance and distribution in young seedlings would 

 be of interest, and might possibly throw some light on their formation." 

 " The seeds were germinated upon the purest filter paper, and were 

 moistened with distilled water." Germination soon takes place, and as 

 soon as th3 plants are six or eight days old the primary leaf can be 

 detected between the cotyledons ; the crystals can now be seen in the 

 petioles of the cotyledons. Various experiments were made with the 

 young seedlings to try and ascertain from what source the calcium and the 

 oxalic acid were derived, and it appears that both are produced from the 

 reserve-food of the cotyledon. — G. S. S. 



Leaf-adaptation to Habitat. 



Climatic Adaptation in the Leaves of Seychelles Plants 



(Beih. Bot. Cent. bd. xii. ht. 3, pp. 304-342 ; tables 7-9).— Herr Max 

 Fabrioiufl has made an anatomical examination of the leaves of twenty- 

 five Seychelles plants, arranged according to the habitat in which they 

 occur (tall trees in woods, shrubs of the undergrowth in woods, soil 

 plants, epiphytes, and small trees growing in the open). The results are 



