LINNEAX SOCIETT Oh' LONDON. XXVU 



eagerness with which thirty years ago German botanists accepted 

 Schleiden's theory that the pollen-tnbe constituted the nucleus of 

 the ovary instead of acting only as its fertilizer, and that the so- 

 called male element was reaUy the female, Endlicher at once mo- 

 difj'ing accordingly the terminology of the Supplements of his 

 ' Genera.' Lichens in their internal texture consist of two classes of 

 bodies, which have received the names of Hyphae and Gonidia, va- 

 riously intermixed or arranged in distinct layers — the outer coating 

 of the thallus consisting exclusively of hyphae (which, indeed, make 

 up the great mass of the thallus), the gonidia being all entirely 

 internal. The hyphae, it is now said, are the sole constituents of 

 the real Hcheu ; the gonidia are accessory bodies, which, although in 

 the thaUus intimately connected with the hyphae, are in some cases, 

 when freed from the lichen, capable of independent existence and re- 

 production. It has been shown that these gonidia in that state are 

 exactly similar to, and even identical with, certain free bodies 

 hitherto classed as Algae ; therefore, it is said, all lichen -gonidia are 

 Algae. It has been seen in a course of careful observations that the 

 hyphae attach themselves to the gonidia they surround, and some of 

 these lose the green matter they contained ; therefore, it is added, 

 these hyphae which constitute the thaUus derive their nutriment 

 from the gonidia. Moreover the spores of a lichen {Collema) have 

 been actually and successfully sown by Bees on an alga {Nostoc), 

 which has gradually been converted into the Collema, thus proving 

 the parasitism of the one on the other ; therefore, again, it is con- 

 cluded, all lichens are parasitical on Algae, — a series of conclusions 

 founded on a very small number of facts. If RhinanthtLS is a para- 

 site, it does not follow, and no one would contend, that all Scrophu- 

 larineae are so. Admitting in like manuer, for argument's sake, the 

 parasitism of the Collema, and that it may be a normal one, that 

 does not prove the parasitism of the great mass of lichens, which, 

 to say the least of it, must be a very singular one. A true parasite 

 feeds and lives upon its victim, without much injury when, as in the 

 case of the Mistletoe or of certain epiphyllous fungi, it has fastened 

 upon a plant vigorous enough to provide food for itself and its guest, 

 as well as to resist the evil effects of the disturbance of its system — 

 but more frequently, as in the case of the Orohanche priiinosa in 

 Sicilian bean-fields, or of a large proportion of parasitical fungi, to 

 the exhaustion and final death of the victim, followed by the pre- 

 mature end of the parasite itself, if it has not had time to go through 

 the last necessary phases of its life by the maturation of its seeds 



