ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 775 



often split and fringed in the upper part ; peridium composed of large 

 colourless cells ; spores brownish or orange-coloured, subglobose when 

 mature, formed in* moniliform rows. Spermogonia punctiform, 

 forming minute dark-coloured pustules in discoloured spots on the 

 upper surface of the leaves. Mycelium infesting the leaves and stems 

 of different Pomefe." 



As regards the genetic relationship of particular species of Gym- 

 nosporangium with particular species of the secidial form, the geo- 

 grai^hical distribution of the dilferent species of the two forms 

 presents great difficulty in the way of the specific identification 

 proposed by Oersted and Eathay.* Artificial cultures of spores of 

 the various species of Gymnosporangium on leaves of Pomeee were as 

 a rule without result ; and when results were obtained, they were 

 difficult to reconcile with the views of these writers. "When 

 spermogonia did appear it was, at least in some cases, ]irobably due 

 to the presence of the mycelium of a Bcestelia in the leaves. Pro- 

 fessor Farlow considers, therefore, that the assumed genetic con- 

 nection of these two genera is a question which requires further 

 investigation before it can be considered as satisfactorily established. 



Cancer of Apple Trees. f — E. Goethe claims to have determined 

 the cause of the cancer (Krehs) of apple trees to be the growth of the 

 fungus Nedria ditissima in the cortical parenchyma, as E. Hartig had 

 previously shown to be the case in the cancer of the copper beech. 

 He succeeded in propagating the parasite in the diseased places both 

 from conidia and from ascopores. The same fungus also produces 

 cancer on various kinds of pear trees ; each can be propagated on the 

 anther, and the conidia or ascospores of the Nectria from the apple 

 produced cancer in the beech and sycamore, and conversely. The 

 cancer in all these trees is therefore due to the same cause ; and the 

 best mode of preventing its attack is to protect the trees as far as 

 possible from injury to the bark, and when this does occur, and the 

 disease begins to manifest itself, to cut out the whole of the diseased 

 tissue, and anoint carefully with warm coal-tar. 



Peziza Fuckeliana and Sclerotiorum.J — E. Pirotta has afresh 

 investigated the genetic connection of Botrytis cinerea, Peziza 

 Fuckeliana, and Sclerotium echinatum, and considers it conclusively 

 established that they are metagenetic forms of the same species, viz. 

 the conidial, ascophorous, and mycelial generations. The experiments 

 were performed with the necessary precautions to prevent the intru- 

 sion of error, and the following were the main results : — 



1. Sclerotia of P. Fuckeliana from fallen vine-leaves developed 

 mostly into luxuriant conidiiferous tufts of B. cinerea, one only 

 giving rise to the cupules of Peziza. These conidia sown on young 

 vine-leaves produced abundant Botrytis, and sclerotia perfectly re- 

 sembling those of S. echinatum. 



* See this Journal, iii. (1880) p. 995. 



t Monatsschr. Deutscher Garten, 1880, p. 79. See Bot. Ztg., xxxix. (1881) 

 p. 228. 



X Nuov. Giorn. Bot. Ital., xiii. (1881) pp. 130-5. 



