ZOOLOGY AND BOTANY, MICROSCOPY, ETC. od 



composed of roundish cells, which can only with difficulty be separated 

 from one another. From these springs the layer of conidia which 

 covers the upper surface of the pileus. The conidia are of an ovoid 

 form, reddish brown, about 7 jx long and 4 /a broad. When ripe they 

 fall off spontaneously and form a dense umber-purple-brown layer of 

 spores 9 p, long and 5 /a broad, filled with finely granular protoplasm. 

 In the tubes is no true hymenium, but the colourless unthickened ends 

 of the hyphae project without any definite arrangement into the tubes, 

 and produce at their apices the spores, which resemble the conidia in 

 every respect. 



Alternation of Generations in some Uredineae.* — The follow- 

 ing is an epitome of the most recent experiments of M. Cornu on the 

 cultivation of the spores of various Uredinese : — 



^cidium pint, gathered on the 16th May, was sown during the 

 following night on five plants of Senecio vulgaris. Two of these 

 perished at once ; on June 1st the circular uredo-pustules were seen 

 on the stem of two of the others, and shortly afterwards on the third, 

 and from there advanced to the leaves. A fortnight later a few teleu- 

 tospores were observed, the teleutoform being identical with Coleo- 

 sporium senecionis. A second sowing on Senecio vulgaris produced no 

 result, and the same was the case with S. sylvaticus, coriaceus and 

 crassifolius and Sonchus oleraceus. This alternation had been suggested 

 by de Bary in 1874. 



Spores of ^cidium urticce, gathered from Urtica dioica, were sown 

 upon Carex hirta. After nineteen days uredospores appeared on the 

 leaves, and seven days later the teleutospores of Puccinia caricis. 

 No result was obtained on Carex riparia. This alternation was also 

 indicated by Magnus, in 1873. 



Spores of ^cidium rhamni, from BTiamnus catharticus, were sown 

 on May 18th, on two pots containing seedling oats; on June 11th 

 pustules of Uredo rubigo-vera made their appearance. On June dth 

 the experiment was repeated ; on June 20th a great number of uredo- 

 pustules appeared, rapidly increasing. On July 9th teleutospores of 

 Puccinia coronata were seen on the lower leaves. This alternation 

 was also suggested by de Bary in 1864. 



The uredospores of Melampsorella, from MoeJiringia trinervia, 

 sown on Alsine media, germinated after about nine days. 



The teleutospores of Puccinia dianthi, also from Moehringia tri- 

 nervia, sown on April 28th on Alsine media and Stellaria holostea, 

 germinated on May 17th, without the intervention of uredoform ; as 

 Cornu had previously observed in the case of P. malvacearum ; a pro- 

 cess which he considers probable in all puccinia s which germinate 

 directly. 



-Slcidinm columnare.t — This parasite of the silver -fir, which 

 makes its appearance on the under side of the leaves, in the form 

 of columnar yellow bladders filled with spores, has not yet been 



* Bull. Soc. Bot. France, xxvii.(lSSO) pp. 179-83; and Comptes Rendus, xci. 

 (1880) pp. 98-9. 



t Allgem. Forat.-u. Jagdzeit., 1880. See Bot. Ztg., xxxviii, (1880) p. 618. 



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