Leaf Curl and Plum Pockets. 323 



cent and finally a rupture occurs at the apex and the spores are 

 shot out suddenly. Usually the spores are all shot out together 

 from a single ascus. De Bary* and Rathayt both placed freshly 

 gathered specimens of Exoasciis on a glass slip in a moist atmos- . 

 phere and after several hours the glass was covered a distance of 

 I cm. from the specimen with the spores, which formed a white 

 ring around it. 



When the fungus is mature the affected parts of the plant pre- 

 sent a whitish or mealy aspect caused by the numbers of asci and 

 free spores. 



Each spore in water or in nutrient solutions is capable of pro- 

 ducing, by a process of budding similar to that of the yeast plant, 

 smaller and similar cells. In water the parent spore becomes by 

 this process smaller also. This frequently takes place within the 

 ascus when the spores are not expelled at maturity, so that after a 

 while the ascus is quite well filled with these small conidia. 

 DeBary,;}: Brefeld§ and Sadebeck|| record the results of attempts 

 to grow the spores in artificial media. In no case was a mycelium 

 observed to develop, but budding always took place where any 

 growth appeared. B}^ placing spores on the young leaf buds, 

 or better on the leaves of seedlings, Sadebeck*y succeeded in 

 observing the entrance of a mycelium in the leaves of Alnus. 

 The species experimented with was Exoascus tosquinetii (Westend) 

 Sadeb. The mycelium was observed to enter through the stomata 

 into the tissues. 



We can now enter into a more detailed discussion of the hyper- 



* Ibid. 



t Ueber die Hexenbesen der Kirschbaume, und Exoascus wiesneri n. sp' 

 Sitzungsb. d. Math.-Naturw. Classe d. k. Akad. d. Wiss. Bd. LXXXIII, 

 Abth. I, p. 280, Wien, 1881. 



i Exoascus pruni etc. Beitrage z. Morph. u. Phys. d. Pilze, Erst. Reihe, 

 Abgd. a. d. Senkenb. Naturf. Ges. Bd. V. pp. 185, 186 ; 1886. 



§Unters. a. d. Gesammtgeb. d. Mykol. Heft IX, pp. 142, 144, Miinster, 1891. 



II Die parasitischen Exoasceen. Abgdruck. a. d. Jahrb. d. Hamb. Wiss. 

 Anst. X, 2 p. 13 ; 1893. 



^Unters. ii. d. Pilzgattung Exoascus und die durch dieselbe um Hamburg 

 hervorgerufen Baumkrankheiten. Abgedruck. a. d. Jahrb. d. Wiss. Anst. p. 

 102 ; 1883. Hamburg. 



Die parasitischen Exoasceen. Ibid. X, 2, p. 13; 1893. 



