REPRODUCTION, VEGETABLE (VEGETABLE OVUM). 



228 



upon their upper surface thecae and paraphyses 

 like those of a Peziza. In other genera 

 MM. Tulasne found that the ascophorous 

 receptacles are preceded by capsules which 

 produce, instead of the linear sporules above 

 mentioned, cylindrical spores of a much larger 

 size, each of which is supported at the 

 extremity of a pedicle of its own. 



42. Thus in the plants under consideration 

 we find that, without counting the sporules 

 which are produced by filaments rising directly 

 from the stroma, there are no less than three 

 varieties of spore-like structures which can 

 be easily distinguished from each other. All 

 of these may be produced upon the same, 

 individual, and one instance is recorded 

 in which a cupule of a Peziza was found, 

 which bore among the normal thecae, para- 

 physes with innumerable, slender, linear 

 sporules at their extremities. As has been 

 already hinted, the capsules which contain 

 acrogenous spores, have been hitherto con- 

 sidered as belonging to genera distinct from 

 those represented by the ascophorous recep- 

 tacles with which they were found associated. 

 The genus Cytispora is characterised by a 

 structure which corresponds completely 

 with that of the capsules described above 

 in Rhytisma ; and other genera as e. g. 

 Sporocadus have a similar relation to the 

 capsules, containing the larger variety of 

 pedunculated, cylindrical spores. 



43. In order to facilitate the description of 

 these various structures, a nomenclature has 

 been devised by MM. Tulasne, which may 

 be adopted with advantage. The minute, 

 linear sporules, which are produced at the 

 extremities of branched filaments, like the 

 paraphyses of Sphaeria, are called spermatia. 

 The cylindrical bodies of much larger size, 

 which are borne each at the extremity of a 

 stipitiform cell, are named stylospores ; while 

 the term spope is reserved to those which are 

 formed in the interior of a theca. 



43. big. In a third " Memoire " which has 

 appeared since the above paragraphs went to 

 press, MM. Tulasne have further prosecuted 

 their researches on this interesting subject. 

 The following is an abstract of their account 

 of the development of a Pyrenomyces (Ce- 



nangium), which inhabits the bark of dead 

 branches of the black alder (Rhamnus Fran- 

 gula). The plant, in its natural position, is 

 represented inj^g. 148. The mycelium ramifies, 

 in all directions, in the substance of the inner 

 bark of the dead branch. From its filaments 

 there spring, at irregular intervals, the re- 

 ceptacles, which as they develope, burst 

 through the outer bark and epidermis and 

 exhibit the various forms represented. The 

 simplest variety( fig. 148. a) resembles in struc- 

 ture the organ described in 49. as occurring 

 in Scutula. In form, it is rounded, but at 

 the same time somewhat conical. The stylo- 

 spores (Jig. 149. a) which it contains, are 



Fig. 149. 



a, group of stylospores, with a fragment of the wall 

 of the receptacle in which they are enclosed; 

 b, similar group of spermatia. About 300 diarn. 



curved, crescentic bodies, supported on pedi- 

 cles, which have an arrangement perfectly 

 similar to that observed in Scutula. The 

 receptacles or cupules in which thecae are 

 produced are deserving of great attention. 

 In the early condition, their form is cyathoid 

 (fig. 148. c), and they resemble those de- 

 scribed (41.) in Rhytisma. They contain at 

 this time, innumerable spermatia (fg. 149. 6), 

 these being supported on filaments which 

 spring from the inner surface of the cup, as 

 well as of its margin. As the organ grows, 

 it expands, and finally becomes discoid 

 (fig. 148. b}, when it possesses the structure 



Fig. 150. 



Fig. 148. 



Part of a dead branch of Rhamnus Frangula, with Vertical section of discoid receptacle of Cenangium, 

 receptacles of Cenangium. (Slightly magnified) about 300 diam. 



