ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 221 



leaf, and the epidermal cells and hyphal branches pass down between the 

 cells and permeate the intercellular spaces. 



Phellomyces Sclerotiophorus.* — T. Johnson records an attack of 

 this fungus on potatoes. It forms minute sclerotia on the skin of the 

 tuber ; the mycelium penetrates the cortical cells, giving the skin a 

 scabbed appearance ; in a more advanced stage it causes dry potato-rot. 

 The cells of the potato are killed, but the starch-grains remain essen- 

 tially unaltered, and a white dry powdery substance appears in the 

 tuber. The author recommends the soaking of seed tubers in a weak 

 solution of formalin or other fungicide before planting. This treatment 

 was found by experiment to have destroyed the fungus without injuring 

 the potato. 



American Uredinese.t — John M. Bates notes the finding of the 

 tecidia of Puccinia Phragmitis in Nebraska on four different hosts, 

 three species of Rumex and one of Rheum. 



W. A. KellermanJ summarizes the infection experiments and their 

 results, conducted by him during the past year. He worked with the 

 teleutospore, and in nine cases he records the successful growth of the 

 tecidia on a separate host-plant. In some cases there was more than 

 one host discovered for the recidial stage. He records also the failures 

 to induce infection, a long and equally instructive list. 



The same author commences an index to Uredinous culture experi- 

 ments, with list of species and hosts for N. America. In a preliminary 

 note he gives an account of work done on the life histories of rusts. He 

 carries the host list alphabetically down to Euphorbia. 



On the Fertilisation, Alternation of Generations, and General 

 Cytology of the Uredinese.|| — V. H. Blackman publishes a preliminary 

 statement as to the result of his research on Uredineje. He reviews the 

 opinions held on the sexuality of the Uredineae and proceeds to record 

 the results of his own observations. After careful examination he finds 

 that the spermatia, though now functionless, have all the characteristics 

 of male cells. He verifies the bi-nucleate condition of the cells, both of 

 hyphas and spores, from the gecidium stage onwards to the teleutospore, 

 which is also bi-nucleate in the young stage, and uni-nucleate when 

 mature. He does not accept this fusion as sexual, but rather considers 

 it a reduction-process as in the spore-mother cells of the higher plants, 

 and followed in both cases by the tetrad division — in the teleutospore 

 the production of the four sporidia. These are uni-nucleate, as are 

 also the cells in the early stage of the gecidium. The bi-nucleate con- 

 dition is reached by the passage of a nucleus from a vegetative cell into 

 the spore-mother cell of the gecidium. Blackman considers this cell to 

 be the female fertile cell, and looks on this association of two nuclei as 

 an act of fertilisation. They do not fuse until the teleutospore is 

 formed. His view is that formerly the ascidia were fertilised by the 



* Econ. Proc. Roy. Dublin Soc, i. (1903) pp. 1G1-5. 



-I- Journ. Mycol., ix. (1903) pp. 219-20. ' % Tom. oil,., pp. 225-38. 



§ Tom. cit., pp. 244-57. U New Phytologist, iii. (1904) pp. 23-7. 



