854 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Passiflora vitifolia. By W. B. H. (Bot. Mag. t. 7936).— Native of 

 Tropical America. Nat. ord. Passifloracece ; tribe Passiflorece. The 

 leaves are deeply 3-lobed, and the flowers crimson. — G. H. 



Parasitism in Fungi, On the Origin of. By G. Massee {Ann. 

 Bot. xviii. April 1904, p. 319-320). — The full paper on this important 

 subject is found in the Phil. Trans. Boyal Society B. cxcvii. 1904, p. 32. 

 The reference quoted above gives the author's abstract of his paper. Up 

 to the present no definite explanation has been offered as to why a given 

 parasitic fungus is often only capable of infecting one particular species 

 of plaut. This, however, is well known to be the case ; for although the 

 spores of fungus-parasites germinate freely on the surface of any plant 

 when moist, infection takes place only when the spores germinate on the 

 particular species of plant on which the fungus is known to be parasitic. 

 The author considers this apparently selective power on the part of the 

 fungus to be due to chemotaxis. 



This conclusion was arrived at from the results of a number of experi- 

 ments conducted with various species of fungi, including saprophytes, 

 facultative parasites, and obligate parasites. The chemotactic properties 

 of substances occurring normally in cell- sap were alone tested ; amongst 

 these were saccharose, glucose, asparagin, malic acid, oxalic acid, and 

 pectase. In those cases where the specified substance or combination 

 of substances in the cell-sap, assumed to be chemotactic, could not be 

 procured, the expressed juice of the plant was used. 



The experiments proved that saprophytes and facultative parasites are 

 positively chemotactic to saccharose, and this substance alone is sufficient 

 in most cases to enable the germ-tubes of facultative parasites to penetrate 

 the tissues of a plant, unless prevented by the presence of a more potent 

 negatively chemotactic or repellent substance in the cell-sap. 



Immune specimens of plants belonging to species that are attacked by 

 some obligative parasite owe their immunity to the absence of the sub- 

 stance chemotactic to the parasite. 



In the full paper the results are given in tabulated form. — A. D. C. 



Parichnos in recent Plants, On the presence of a. By T. G. 



Hill {Ann. Bot. xviii. October 1904, p. 654). (Abstract of a paper read 

 before Section K at the Cambridge meeting of the British Association.) — 

 Notes the presence of degenerating tissue and resulting mucilage canals in 

 the leaf of Isoctes Hystrix. It is suggested that the canals represent the 

 parichnos occurring in Lcpidodendron and other fossils. — A. 1). C. 



Palisota Schweinfurthii (syn. Dichorisandra Thysiana). By H. 

 Conrad (Die Gart. No. 47, p. 553, August 20, 1904).— M. Charles Pynaert 

 described this plant in 1902 in the " Revue de 1' Horticulture beige " 

 as Dichorisandra thysiana, but seemed to have his doubts about the 

 naming. Since the plant has flowered in cultivation it has turned out to 

 be Palisota Schwcinfurtliii. A grand foliage plant with white flowers. 



G. B. 



Palaeozoic Seed Lag-enostoma Lomaxi, On the Structure of 

 the. with a statement of the evidence upon which it is referred 

 to Lyginodendron. By F. W. Oliver and D. H. Scott (Ann. Bot. xviii. 



