382 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Pycnochijtrium, in which the zoosporangiate sori escape from the host- 

 plant. The cells in which they are formed grow to very large di- 

 mensions, and in some species the neighbouring cells also share in the 

 transformation. The galls examined were found on Mercurialis p&rennis, 

 Anemone nemorosa and Adoxa Moschatellina. In each case the author 

 describes the normal host cells, and contrasts them with the deformed 

 cells that serve as hosts to the parasite. The latter increase to a very 

 large size ; the neighbouring cells may divide repeatedly, but they do not 

 become so large. The host-cell is filled with a somewhat thick plasma, 

 the chloroplasts are abundant, but contain little or no starch ; the nucleus 

 lies close to the Synchytrium spore and attains a very large size ; the 

 nucleoli also show considerable increase in volume. The substance of 

 the nucleus is traversed by a branching system of canals, which unite in 

 a large opening towards the side of the nucleus next the parasite. Details 

 are given of the division of these nuclei. 



The resting spores of Synchytrium have a thick wrinkled chitinous 

 membrane, the interior plasma contains numerous vacuoles : a large 

 nucleus lies in the centre with a distinct nuclear wall and two or three 

 small nucleoli. 



Monascus purpureus.* — Andre Piedallu noted that during the opera- 

 tion of tanning leather with oil various changes took place in the 

 substances used. Several bacteria and moulds have been isolated that 

 play important parts in the processes, and notably Monascus. This 

 fungus has been studied by various authors on account of its rather 

 remarkable morphology. Piedallu examined it for its physiological 

 properties and grew it on a large number of substrata, noting the colour 

 effects, etc. He finds that Monascus acidifies the oils employed, thickens 

 them and colours them brown, and secretes an oxydase. He concludes 

 that it plays an important part in the tanning process. 



Observations on the Morphology of the Oidium of the Oak.f 



The recent appearance and rapid spread of this parasite have roused the 

 interest of plant pathologists. Teodoro Ferraris has made a thorough 

 study of the fungus and compared it with others recorded on the same 

 host. It attacks chiefly young trees, covering the leaves with a white 

 felt. The author describes the different phases of growth, mycelium, 

 conidiophores, conidia, etc., and then takes up the question of identity. 

 By most authors it has been referred to Microsphsera Aim, but Ferraris 

 disputes this, and considers rather that it is Oidium quercinum Thum. 

 var. yemmiparum. The ascophorous form has not yet been detected, 

 but he thinks that it is probably either Microsphsera densissima or 

 M. quercina, both of which are parasites of the oak. 



Specialisation of Sphserotheca Humuli within the genus 

 Alchemilla.J — J. A. Steiner has conducted a large series of infec- 

 tion experiments on plants of this genus, which he divides into various 

 groups ; he took ascospores and oidia from representatives of these 

 groups, and made inoculations on the whole series of plants. The 



* Comptes Rendus, cxlviii. (1909) pp. 510-13. 



t Ann. Mycol., viii. (1909) pp. 62-73 (1 pi.). 



\ Gentralbl. Bakt., xxi. (1908) pp. 677-736 (1 pi. and 3 figs.). 



