11 



by its author, and has afterwards been referred to another genus, by 

 another authority, and the latter is accepted, tiie name of the first 

 authority is placed in a parenthesis and followed by that of the sec- 

 ond, thus : " Ramaliua ceruchis (Ach.) De Not." Acharius called 

 the plant " Borrera ceruchis," while De Notaris placed it in its 

 proper genus, Ramalina. Some authors insist that when a variety 

 is raised to the rank of a species, the name attached should be 

 that of him who gave the name to the variety. But the better rule 

 appears to be that stated by Tuckerman (Genera, p. 179) that "the 

 name which may happen to be given to a variety has no precedence ; 

 but may be adopted or not, if the plant be taken up as a species. 

 The other method has at least the objection that it makes the earlier 

 writer whose variety-name it is sought to elevate into a species-name 

 responsible for an opinion which he has expressly disclaimed." The 

 same rules apply to genera and their divisions. The authority for 

 a species-name is either a published description or the distribution 

 of the species in a published collection of exsiccati. Unpublished 

 herbarium names are not entitled to preference over subsequently 

 published ones, nor can names be -preempted by anticipation. The 

 collection should be occasionally overlooked to see if insects or mould 

 have made their appearance, in which case the plants should be poi- 

 soned. But this will seldom be necessary if the collection is kept in 

 a dry place. Handsome specimens, neat mounting, clearly written 

 labels, and methodical arrangement, add greatly to the appearance 

 of a collection. The genera should be placed in distinct wrappers. 

 In short, the general rules applicable to all collections of plants will 

 serve for Lichens also. 



CHAPTER II. 



THE LICHEN : ITS STEUCTUEE AND ORGANS. 



A Lichen is a cryptogamic plant of the order of Thallophytes, 

 having neither stem, leaf, flower, or root. It consists of a Thallus 

 containing green cells called Gonidia, which supports the fruit, 

 Apothecium, containing the germinating cells, Spores, which are 

 enclosed in cells or sacks here called Thekes. It also possesses 

 certain minor organs, Spermogones and Pycnides. We will consider 

 each of these parts in order. 



