THE PERITHECIUM OP MELIOLA. 7 



say that this idea is altogether a false one, but investigation of the 

 development of the fruit-bodies seems to show that at least no neces- 

 sary connexion exists between the two phenomena. 



As to the function of the seta?, little or nothing can be stated. The 

 earlier suggestions of Sprengel and Fries (as quoted by Bornet) that 

 they may be organs for the exit of the spores cannot be accepted : not 

 only on the ground of the disproportion between the numbers, but 

 also because the spores are too large to pass through the setce, even 

 supposing the cavity continuous and ending in an ostiolum, which is 

 not the case. I have often tried to discover conidia or other bodies 

 in connexion with the setce, but have been forced to the belief that 

 they have no function whatever connected with spore-production. 

 One is not now impressed with the necessity for assigning any special 

 function to such structures : if the setce are merely free-growing 

 branches of the otherwise appressed, creeping mycelium, there is 

 nothing surprising in the fact that some differences in form and con- 

 sistency are correlated with their sub-aerial habit. This is at least no 

 more remarkable than that the looser branches of an alga, like Coleo- 

 chcete, should have a facies slightly differing from that of the cell 

 series comprising the lower, creeping, appressed parts of the thallus. 



The collection of setce immediately around the " fruit-body " simply 

 results, immediately, from the vigorous development of hyphas which 

 accompanies the later stages of formation of the perithecium : this 

 mass of setigerous hyphse, which seems comparable with the formation 

 of kaustoria and such-like organs in other fungi during the fruit de- 

 velopment, was called the " receptacle " by Bornet. As to a possible 

 protective influence of the circles of setce, the question must be left open 

 until we know more of the conditions : in some cases, at any rate, the 

 setce do not arise until the perithecium is completely formed, and the 

 spores nearly ripe. 



The perithecium, when completely developed, is a globular or 

 sub-globular body, consisting of a shining black or brown external 

 case, the outer thick walls of which appear regularly embossed, and 

 an internal mass composed of asci and spores, &c. The embossed 

 pattern on the outer walls results from the thick-walled cells, of which 

 it is composed, projecting at their free surfaces : where the cells join 

 each other, forming polygonal figures, they do not so project. 1 What 

 may be termed the base of the perithecium is sessile on the mycelium : 

 1 See Bornet's figures, loo. cit., plates 21 and 22. 



