THE PERITHECIUM OF JIELIOLA. 15 



in the same perithecium one finds asci in which one, two, or three 

 spores develop at the expense of their presumably weaker neighbours 

 (fig. 38), in other cases the number two appears constant, only one 

 complete division occurring in the ascus (fig. 38), while in one case to 

 be referred to later, the asci normally produce eight two-chambered 

 spores (fig. 43). 



On germination, which may take place soon after the emission from 

 the ripe perithecium, the spores seem to behave generally in the same 

 manner ; one or several simple protuberances emerge from any of the 

 partitioned chambers (see fig. 40), and proceed to develop into a 

 typical mycelium, often with a preliminary formation of the rudi- 

 mentary haustoria referred to in an earlier part of this paper. This 

 mycelium grows rapidly in moist weather, forming branches, setae 

 and fruit-bodies as before. In some seasons the leaves of various 

 plants may be seen covered with hundreds of these young mycelia, 

 which dry up when the atmosphere does, only to renew their growth 

 with the rains. 



Before passing on to the consideration of the pathological influence 

 of these fungi, and of their systematic position, I will record a few 

 details concerning a form of Meliola which varies somewhat from the 

 typical cases hitherto considered ; at any rate, it seems to differ more 

 from the six or eight forms to which the above description refers, than 

 they do among themselves. 



The species to be examined has only been found on the leaves of 

 Pavetta indica, and its mycelium forms more spreading and less de- 

 fined patches on the leaves of that plant than the easily recognisable 

 sooty patches of the other Meliolas. The main features of its myce- 

 lium, &c, are shown in fig. 41, and differ chiefly in the delicate 

 straggling hyphse, with a paler brown colour and no trace of haustoria. 

 The branching is very irregular, and somewhat like that of the form 

 figured at fig. 3, but the short, lateral branchlets are not always ovoid, 

 but often have sinuous, almost angular outlines, reminding one of the 

 similar structures in Asterina, except that the latter bear distinct 

 haustoria. The setae are here quite simple, short, and not so hard and 

 brittle as usual ; they are also produced in smaller numbers than in 

 the more typical species. 



The greatest peculiarities, however, are offered by the fruit-bodies, 

 or perithecia. Each of these arises as before by the successive dividing 

 up of a short, lateral branchlet (plate 44, fig. 42), with this difference, 



