ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 791 



Ascochyta minutissima, Hendersonia Camellise, Bhabdospora advena, and 

 Pestalozzia Camellise. 



Parasitism of Tuber.* — Dr. O. Mattirolo has established the fact that 

 some rhizomorphs parasitic on roots perfectly resembling those known as 

 mycorhiza by Frank f and others, give rise, in circumstances not accurately 

 defined, to receptacles of species of Tuber, especially to T. excavalum Vitt. 

 and T. lapideum n. sp. In both these species are internal cavities formed 

 by a depression of the peridium, and opening externally by an aperture. 

 This winding cavity is clothed by a number of dark-brown filaments united 

 lengthwise into bundles, identical with the rhizomorphs of many genera of 

 fungi. These filaments were determined by the author to proceed 

 indubitably from the pseudo-parenchyma of the peridium, the continuity 

 of the hyphfe being, however, lost with age. From the cavity in the receptacle 

 these rhizomorphous hyphaD extend in all directions, forming a mycorhiza, 

 in all respects resembling that found on the roots of Cupuliferge, The 

 parasitism of the truffle on roots Dr. Mattirolo considers to be amply 

 demonstrated. 



Clisetomium.l — The reproductive structure of this genus of Ascomycetes 

 having been differently interpreted by different observers, the life-history 

 has again been subjected to careful investigation by Herr F. Oltmanns. 

 The species most fully worked out is C. Kunzeanum, grown on decoction of 

 fruit. From the spore proceeds, as described by Zopf, a vesicle, from 

 which spring the mycelial filaments spreading in all directions and 

 branching abundantly in favourable nutrient solutions. The filaments are 

 smooth or torulose according to the conditions of growth. 



From the mycelium are developed undoubted ascogones, in which two 

 6j)iral bands can be clearly distinguished ; the coils may either be elevated 

 above the pedicel or may embrace it ; the pedicel is occasionally wanting, 

 apparently an abnormal structure. In many cases the existence of a 

 pollinodium can be distinctly made out, agreeing in essential points with 

 that of Eurotium. The pollinodium appears always to spring from the 

 pedicel of the carpogonium ; but its presence is often very uncertain ; and 

 in other cases it is clearly wanting, always when the carpogonium is coiled 

 round its own pedicel. 



The envelope, in which the ascogone is eventually completely inclosed, 

 originates from branches of the hypha^ out of which the ascogone springs. 

 The result is the production of a roundish ball with comparatively smooth 

 surface, from which project the separate hairs characteristic of the genus ; 

 and the wall of the perithecium is then fully formed inclosing the archicarps. 

 The author never saw perithecia which did not inclose an ascogone; but 

 several ascogones may be inclosed in a common envelope. The develop- 

 ment of the perithecium may take place in four different ways, which, 

 however, run into one another, viz. : — (1) The hyphse which constitute the 

 envelope spring from immediately beneath the ascogone, as its pedicel ; 

 (2) Hyphfe are formed from the entire pedicel which interweave to form the 

 envelojie ; (3) The pedicel of the ascogone and the adjacent hyphae form 

 numerous filaments ; (4) The enveloping hyphfe are formed in large numbers 

 before the production of the ascogone, which is often pushed in at a much 

 later period. 



From careful longitudinal sections of perithecia, which are very diflicult 



* Atti R. Accad. Torino, xxii. (1887) pp. 464-72, and Malpighia, i. (1887) 

 pp. .35'J-G9 (1 pi.). t See this Journal, 1886, p. 113. 



X Bot. Ztg., xlv. (1887) pp. 193-200, 209-18, 225-33, 249-54, 205-71 (1 pi.). Cf. 

 this Juumal, 1882, p. 376. 



