DR LAUDER LINDSAY ON NEW LICHENICOLOUS MICRO-FUNGI. 517 



dimensions or form. The proximal articulation is frequently colourless, while 

 the terminal one is deeply coloured. In size the articulations always vary on the 

 same filament — the oldest or terminal one being the largest — the younger being 

 at least narrower in proportion to their youth. Thus the terminal spore is 

 frequently twice as large as the proximal one, the increase in dimension relating 

 to breadth rather than length. In maturity, and when free — thrown off from 

 their filaments — there is much less difference in the form and size of the spores. 

 In form they are generally oblong, with flattened ends, unless in the terminal spore, 

 which has its free or upper end rounded, even while attached to the filament. 

 Occasionally the corners of all the free articulations or spores are similarly 

 rounded. Sometimes the spores are oval or ellipsoid. Their length is generally 

 about 00025". In structure they are usually simple, with or without double con- 

 tour ; sometimes, though rarely, granular ; occasionally also having a central sep- 

 tum, or faint indications of the existence of one or more septa ; more frequently 

 containing one or more (two to three) spherical nuclei. Where there are two nuclei, 

 they are generally arranged near the poles or extremities of the spores, to which 

 they sometimes then give a sub-physcioid aspect, that which occupies the distal 

 end of a spore being always the larger. This bi-nuclear character may attach to 

 all the spores in a given specimen; and then, as well as in other cases, the spores 

 in question resemble many lichen-sporidia. Sometimes chains or groups of spores 

 of equal size and uniform character occur in numbers of four to eight, apparently 

 the result of agglutination after maturity, and gaining the free state. In some 

 cases the concatenate condition might be supposed to arise from simple absorp- 

 tion or disappearance of the pedicle of the filament; but in such a case the 

 constituent articulations would probably retain, even in age, their differences in 

 size. The site of Torula lichenicola is the thallus or apothecia (or both) of various 

 lichens, mostly crustaceous, and belonging to the Lecanorw or Leciclece. It is 

 much more common in Lemnora subfusca than in any other species in my own 

 experience ; and it is so markedly more common on Irish specimens of that 

 Lecanora — mostly from the vicinity of Cork — as to give rise to the supposition 

 that there may be some connection between the greater frequency of the parasite 

 in Ireland and the (alleged) greater moistness of the climate of that country. 

 There is, moreover, a frequent connection between the growth of the parasite and 

 degeneration of the thallus or apothecia of the host ; sometimes at least, obviously 

 as productive of degeneration, e.g., when the Torula overspreads the disk of 

 L. subfusca, rendering it as black as that of L. atra On the thallus of lichens it 

 may be scattered generally over the surface ; or only over particular parts thereof, 

 e.g., the periphery, or it may occupy only the areolae or verrucse. On the apothecia 

 it may occur only on the disk, or both on the exciple and disk. The apothecia 

 affected by the parasite are frequently degenerate or deformed ; the disk has 

 sometimes disappeared, and the whole apothecium has acquired an irregularly 



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