OF ARTS AND SCIENCES. 19 



its origin, for it is certainly without analogy that any form of repro- 

 ductive bodies should be at one and the same time male organs, and, 

 as stated by Moller, " conidia with slightly weakened functions," un- 

 less indeed we consider as in any way analogous the supposed rever- 

 sion to a vegetative condition of the pollinodium or fertilizing cell of 

 certain Ascomycetes. In view of the fact that these spermatia or 

 conidia possess the function of non-sexual reproduction to by no means 

 the normal extent, it is certainly possible that they are to be consid- 

 ered as degraded forms, which by disuse have lost their former sexual 

 function, a function which we find is retained by similar orjrans in 

 other lichens. This view is not without analogy. It is certainly a 

 significant fact, that, as will be seen later, the character of the sper- 

 matia as non-sexual reproductive bodies exists only in those lichens 

 where no form of sexual reproduction has as yet been observed with 

 certainty, and that, in the group of lichens where sexual reproduction 

 exists, all the knowledge that we possess regarding the spermatia 

 points to their sexual character. There was nothing appi'oaching any 

 certain knowledge on this point until 1877, when Stahl published his 

 remarkable observations on certain homceomeric and heteromeric 

 lichens.* A reference to his paper will show that of the species ex- 

 amined by Stahl all but three belong to the CoUemaceae, these three 

 exceptions being members of the angiocarpic and gymnocarpic groups 

 of the heteromeric lichens, about which very little of a definite nature 

 is said. On the subject of the Collemaceae, however, Stahl is much 

 more explicit, and his observations, depending upon careful treatment 

 and accurate observation, seem, if true, capable of satisfactory proof. 

 In brief they are as follows : — Stahl has observed, embedded in 

 the gelatinous substance of the thallus, peculiar hyphfB in the form 

 of more or less definite knots or loose spiral coils. This coiled 

 series of richly protoplasmic cells, designated as the " ascogonium," 

 and corresponding to what is known in certain ascomycetous fungi as 

 " "Woronin's hypha," is continued upwards in a multicellular slender 

 thread, reaching the surface of the thallus by piercing the investing 

 cortex, and designated by Stahl as the " trichogyne," on account of its 

 similarity in function to the organ of that name seen in certain of the 

 Floridege. With the projecting tip of this organ the spermatia come 

 in contact, and adhere to its sticky surface. Although, owing to the 

 small size of the spermatia, protoplasmic union between them and the 

 tip of the trichogyne has not been observed, the subsequent changes 



* Stahl, " Beitrage zur Entwicklungsgeschichte der Flechten." 1877. 



