ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 827 



observed by Strasburger in tbe formation of tbe pollen of some 

 phanerogams and of tbe spores of some vascular cryptogams, and in 

 the formation of the endosperm in the embryo-sac. 



The mode of formation of the zoospores of Phytophthora agrees 

 with that already described in the Saprolegnieae. In Pythium the 

 formation of cell-plates is in most cases very doubtful. 



The question of the presence or absence of the cell-nucleus in the 

 sporangia presents many difficulties. In some cases round or len- 

 ticular bodies exhibiting the reaction of nuclein can be made out with 

 certainty. In Leptomitus it is especially distinct, each spore possess- 

 ing one nucleus. In other cases each spore contained two nuclei ; 

 while in others the presence of a nucleus could not be certainly 

 demonstrated. 



The processes which take place in the formation of the zoospores 

 within the sporangia of the Phycomycetes must be regarded as falling 

 within Strasburger's definition of true cell-division. 



Alternation of Generations in the Hypodermige.* — M. Cornu has 

 been able to produce the aecidium of Puccinia arundinacea on Ranun- 

 culus repens from spores, but not abundantly, and always late in the 

 year, viz. in October and November. This species does not attack 

 P. bulbosii8, acer, sceleratus, or Flammula, or Lonicera. Ranunculus 

 acer, bulbosus, and repens are, however, also subject to the attacks of 

 an aecidium derived from TJromyces graminum Cooke ; the ranuncu- 

 laceous plants Aquilegia vulgaris, Aetata spicata, Aconitum Napellus, 

 and Hepatica triloba support aecidia which are considered to be distinct 

 from the above. The puccinia-form of P. arundinacea occurs on 

 Arundo Phragmites ; thus the species inhabits plants of very different 

 characters at different stages of its life-history. 



"Mai Nero" of the Vine.f — 0. Comes has determined that this 

 widespread disease is caused by a production of gum like that to 

 which stone-fruit trees are liable, the result of insufficient nutrition ; 

 and that the fungi which always accompany it are a secondary phe- 

 nomenon only. The best cure is copious manuring, and especially 

 the abundant supply of phosphates and lime-salts. 



Aubernage: a Disease of the Vine. % — For some time past a 

 disease of the vine called " Aubernage " has shown itself at Auxerre 

 in the department of Yonne, with most disastrous results. After first 

 small and then large spots have appeared on the branches, a rapid 

 disorganization of the tissue of the wood commences, which, beginning 

 at the extremities of the branches, spreads downwards to the roots 

 and completely destroys the plant. C. Eoumeguere has proved the 

 existence of three fungi in the diseased branches. Phoma vitis Bk. & B., 

 Phoma pleurospora Sacc. var. forma vitigena, and Sphaerella pampini 

 Thra., and believes that in the joint action of these fungi he has dis- 

 covered the true cause of the disease. 



* Comptes Kendus, xciv. (1882) pp. 1731-4. 



t L'Agricolt. roerid. Portici, v. (1882) pp. 64-72. See Bot. Centralbl., xi. 

 (1882) p. 97. Ci. this Journal, ante p. 229. 



t Revue Mycol., iv. (1882) pp. 1-3. See Bot. Ctntralbl., xi. (1882) p. 98. 



