ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 347 



balls are visible as fine points. On the decay of the leaves the spore- 

 balls are set free. 



Revision of the Genus Hemileia Berk.* — G. Massee describes two 

 new species of this Uredine. Only the uredospores and teleutospores 

 are known, and it is extremely desirable that a search should be made 

 for a possible JEoidium. A complete knowledge of such troublesome 

 parasites is essential, if adequate measures are to be taken to stamp them 

 out. Hemileia vastatrix, the disease of coffee-plants, has been recorded 

 from Asia and Africa ; and there are also species from Australia and 

 America, indicating a wide distribution of the genus. 



Anomalous Fungi. f — D. Jose Esteva cites two cases of the larger 

 fungi which were found growing as parasites on another member of the 

 same species. In one case the secondary fungus was in the usual upright 

 position, in the other it was reversed and the hymenium was uppermost. 

 He discusses the reasons that would explain this anomaly. Either the 

 primary fungus has carried up with it a near neighbour, or the parasite 

 has grown from spores, forming a mycelium and a new growth on the 

 host fungus. 



Gummosis in the Amygdalae.} — W. Beijerinck and A. Rant describe 

 in detail their work on gummosis as affected by parasitic fungi. Wounds, 

 especially in summer and in young twigs, induce a flow of gum. This 

 phenomenon depends on a pathological transformation of embryonic 

 woody tissue due to traumatic excitation. Fully formed wood is never 

 transformed into gum — only the newly formed tissue not yet lignified. 

 The author resumes his work in a series of propositions, thus : — 



That the normal plant produces cytolytic substances, which contribute 

 to the formation of vessels and tracheides. 



Physiological gum which is formed in the process is usually re-absorbed. 

 The flow of gum rests on the excessive activity of these cytolytic sub- 

 stances which are produced by necrobiotic cells, that is, cells in which 

 the protoplasm is dead, but in which the enzymes are still active. 



Poisons, such as corrosive sublimate or the poison produced by the 

 fungus Coryneum, augment indirectly cytolyse in the cambium and in 

 the young secondary wood, and induce the formation of gum canals. 



The authors have found besides Coryneum that Monilia fructigena 

 also favours gummosis, especially in the apricot, and they also found a 

 Cytospora on the branches of a cherry, though its action was somewhat 

 doubtful. The parasites produced strong poison effects, young branches 

 being easily killed, the tissues becoming brown. The formation of gum 

 is confined to the zone between the living and the dead tissues. In all 

 the Arnygdalas examined they were able to produce gummosis wherever 

 there was cambium by means of the fungus Coryneum. 



Poisonous Nature of the Lolium Fungus. § — Eduard Hackel dis- 

 cusses the whole question on the basis of previous work by Wilson, who 



* Bull. Roy. Bot. Gard. Kew, ii. (1906) pp. 35-42 (1 pi.), 

 t Bol. Hist. Nat., vi. (1906) pp. 98-100 (2 figs.). 

 X Arch. Neerl. Sci. Exact. Nat., xi. (1906) pp. 184-98. 



§ Mith. Nat. Ver. Steiermark, 1904 (1905), lii.-lviii. See also Hedwigia, xlv. 

 (1906) Beibl., pp. 92-3. 



