ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 67 



ants which protect the plants against injurious insects. The results of 

 the investigations appear to show that in many plants, the secretion of 

 sugar does much harm, by attracting not only ants, but beetles, bugs, 

 etc., which eat the sugar and also the nectaries, leaves and flowers. 

 This is the case with the orchid Spathoglottis plicata, a shrub-like 

 malvaceous plant, and others. In Hibiscus rosa-sinensis and in Hibiscus 

 tiUaceus, where extra-floral nectaries occur, no sugar is secreted owing 

 to the growth of a fungus in the nectaries, and here the plants are 

 healthy and uninjured by insects. There is no confirmation of Burck's 

 theory that extra-floral nectaries occur near inflorescences, in order to 

 attract ants which serve as a protection against bees and wasps which 

 would bore the flowers. The number of bored flowers stands in no 

 direct relatioii;to such nectaries, but rather in relation to the position of 

 the plants, weather, etc. Moreover, the shapes and positions of the 

 nectaries do not appear to be adapted for ants, and young plants, 

 where most protection is necessary, have no sugar secretion. The ants 

 which are attracted appear to be of a peaceful nature, and unable to 

 afford any protection to plants ; the dangerous ants, which might be 

 of use in this way, are carnivorous and can only be attracted by animal 

 food. The author believes that the real meaning of these nectaries 

 has yet to be discovered, and that new investigations must include 

 plant-physiology as well as biology. 



Influence of Nectaries on the Opening of Anthers.* — W. Burck 

 has conducted investigations with the object of discovering whether the 

 nectaries and other glucose-secreting tissues influence the opening of the 

 anthers by withdrawing water from them. Experiments conducted upon 

 Diervillea rosea, Digitalis purpurea, Oenothera Lamarckiana, etc., show 

 that water is withdrawn from the anthers by osmosis set up by the 

 glucose-containing tissue found in the stamens and corolla. Other 

 flowers, whose anthers behave differently, have similar tissue, but to a 

 very much smaller extent. In a second series of experiments con- 

 ducted upon SteUaria media, Gerastium semidecandrum, G. erectum, 

 Holostewn umbellatum, and many other flowers having a nectary at the 

 base of each stamen, the bursting of the anthers appears to be due to 

 the osmotic influence of the nectaries, not as in the first group, to simple 

 glucose-containing tissue. While in a third series of experiments upon 

 such flowers as Ranunculus acris, Brassica oleracea, Geranium molle, etc., 

 negative results were obtained, the general conclusions seem to show that 

 nectaries and glucose-secreting tissues play an important part in enabhng 

 the anthers to open at the right time, independently of the hygroscopic 

 condition of the air. 



Baegagli-Petrucci, G. — Descrizione di alcuni tricomi de Palme. (Descrip- 

 tion of some trichomes of palms.) Nuovo Giorn. But. Ital., n.s. xiv. (1907) 



pp. 293-5 (1 pi.). 



Colozza, A. — Studio anatomico sulle Goodeniaceae. (An anatomical study of the 

 Goodeniacese.) Tom. cit., pp. 304-26* (2 pis.). 



Proc. Acad. Amsterdam, ix. pt. 1 (1907) pp. 390-6. 



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