Eumycetes. 191 



the Tumours on Veroiiica Chaniaedrys caused bj^ Sovosphaera 

 Veionicae. (Ann. of Bot. XXIV. Jan. 1910. p. 35—43. 1 Plate.) 



A morphological and cytological account of the life-history of 

 Sorosphaera Veronicae. The material examined by the authors occur- 

 red on F. Chamaedrys and the parasite formed swellings on the 

 Sterns, leaves and petioles. 



A vegetative and reproductive stage is distinguished, characte- 

 rised by a difference in the nuclei and in their method of division. 

 In the earl}^ stages of the vegetative phase an amaeba-like organism 

 is to be found in the procambial cells of the host. The amaeba grows 

 and the nuclei divido repeatedly, tili a Plasmodium is formed. This 

 body is not however a true Plasmodium in the sense of Cienkowsky 

 in that it is not formed by the aggregation of amaebae from many 

 spores, but from the growth of a Single spore. Portions of the Plas- 

 modium may be constricted, so that several plasmodia may be 

 found in one hypertrophied plant-cell. The vegetative (ergoplastic) 

 nuclei do not divide by karyokinesis. 



When spore-formation is about to commence differences are 

 observable in both protoplasm and nuclei, which result later in the 

 Separation of the plasma around each nucleus into areas termed 

 amaebulae. The nuclei of the amaebulae then undergo two divisions 

 in the ordinary mitotic manner. The amaebulae (now reduced in 

 size) are found in loosely aggregated masses, which gradually 

 become sphaeroidal; the individual amaebulae at the same time 

 become more distinct and each secretes for itself a cell-wall, and 

 finally the sorosphere is formed which consists of a central cavity 

 surrounded by wedge-like spores. On the ripening of the sorospheres 

 the tumour begins to decay. 



Sorosphaera is similar to Plasmodiophora in that the infected 

 area is only increased by the division of already infected cells, and 

 that neither the amaebae nor their nuclei have any power of pene- 

 trating through the cell wall into a healthy from an adjacent infected 

 cell. The exact method of infection was not observed; infected areas 

 decrease in size towards the growing point of the host, and Single 

 isolated infected cells were traced close to the actual apex. Infection 

 therefore appears to take place in that region. When the invasion 

 is extensive the whole shoot is modified, but when less the growing 

 point frees itself and a tumour is formed on the side of the stem. 



SorospJiaera is closely allied to Plasmodiophora, which genus 

 it resembles not only in its method of growth but also in nuclear 

 details. The final production of soropheres renders it however quite 

 distinct. A. D. Cotton (Kew). 



Borth^vieh, A. \V., Pesisa Willkofnmii on Larix occidentalis Nutt., 

 and Larix leptolepis Gord. (Notes from the royal bot. Garden 

 Edinburgh XXI. Aug. 1909. p. 23—26. 1 Plate.) 



Records the occurrence of larch canker in Larix leptolepis, a 

 species often supposed to be immune, and also in 5 year old seed- 

 lings of the rare and little-known L. occidentalis. 



A. D. Cotton (Kew). 



Brooks, F. J., Notes on Polvporus squamosus, Huds. (New 

 Phytol. Vm. 9/10. p. 348—350. f textfigure.) 



A note dealing with the development of the sporophores and 

 the liberation of the spores. Figures are given indicating the rapi- 



