480 SUMMARY OF CURRENT RESEARCHES RELATING TO 



of sterile cells. As has long been known, the peridial cells are meta- 

 morphosed tecidiospores and aecidiospore initial cells. The central arch 

 of the peridium is formed from the apical eecidiospores of the interior 

 spore chains and the lateral walls from entire peripheral spore chains. 

 The first peridial cells are produced at the centre of the arch and the 

 peridium enlarges from this point centrifugally until the bases of the 

 lateral walls are reached. Its subsequent enlargement is by the basipetal 

 growth and sterilization of the peripheral spore chains. 



Biology of Uredineae.* — E. Fischer gives an excellent account of 

 the papers which have been published during 1913 dealing with the 

 Uredinese. The review is critical, and considers the work of twenty- 

 four authors, who have made contributions from many different stand- 

 points. A full bibliography is given. 



Wintering of Uredospores.t — L. Montemartini gives a review of 

 the results of other investigators on the persistence of the uredospore- 

 stage of cereal rusts during winter. He states that in Italy rust occurs 

 on wild and cultivated GramineEe, which remain green after harvest, 

 and may therefore reinfect wheat at any time. Autumn-sown wheat 

 may thus be directly infected, and in warm and late seasons the disease 

 appears. The uredospore seems capable of resisting several degrees 

 of frost, though on this point the author's observations are not yet 

 complete. Montemartini holds that in Italy it seems probable that the 

 infection of the wheat crop takes place by means of uredospores from 

 diseased plants during the autumn rather than by Eriksson's mycoplasm. 

 The spread of the disease is influenced by the growth of grasses, the 

 summer weather (for when the summer is hot and dry the uredo-stage is 

 succeeded by teleutospores), the period of sowing, and the'autumn and 

 winter weather. 



Internal Spores of Rusts. £ — J. Beauverie, dissatisfied with the 

 explanations suggested of the method by which rusts are able to exist 

 through the winter, has endeavoured to find evidence of the propaga 

 tion of the disease by the seed of affected plants. In the seeds of 

 many cultivated and wild Graminege, he found sori of uredospores and 

 teleutospores, or the mycelium of rust. If the seed is clothed, the sori 

 are produced on the interior of the glumule, and project more or less 

 in the contiguous pericarp ; if the seed is naked, the sori form in the 

 pericarp, usually in the parenchyma of the groove. These sori are not 

 exceptional, but are very frequent in certain species. They are more or 

 less general in barley (Puccinia glumarum). The wild grasses, Brachy- 

 podium pinnatum, Bromis mollis, Agrojiyrum, etc., show the phenom- 

 enon well. The frequency in wheat is not so easy to establish, but 

 the author records clusters of uredospores on the surface of grains of 

 wheat, which have arisen from the sori of the glumules and are re- 



* Zeitschr. f. Bot., vii. (1914) pp. 625-36. 

 t Riv. di Palatog. veg., vii. (1914) pp. 40-4. 

 + Rev. Gen. Bot., xxvbis (1914) pp. 11-27. 





