12 THE CHICAGO ACADEMY OF SCIENCES. 



colorless. The thekes vary in shape, linear, clavate, etc, and are 

 large or small, according to the spores. The latter are variable in 

 form, size and color, as well as in number; they are either simple 

 or divided by transverse septa into cells, usually eight, when they 

 are called eight-locular; if more, pluri or multi localar, but there 

 may be less. When it is also divided longitudinally it is called 

 a muriform spore. The examiner will often find no spores, hence 

 should have fresh plants, particularly of Arthonia. The spore 

 may be less than a thousandth of a millimetre in diameter, but 

 some can be seen with an ordinary lens. Much importance is 

 attached to the colors and shape of the spores. Spermagones 

 have been mentioned. These will exhibit, arising from them, 

 small filaments, which if simple are called sterigmata; if articulate, 

 arthrosterigmata, to which are attached minute bodies (spermatia) 

 which are various in form. Nylander, Minks and others have 

 theorized and written learnedly in regard to their functions. 



It would be desirable to explain further in regard to the 

 spores and other organs entering into lichens, but these can be 

 studied to better advantage after one has acquired some knowledge 

 of the more obvious characters, besides no one can do much with 

 any satisfaction until he has studied our greatest American 

 authority, Tuckerman, and with his works those of the great 

 Lichenologists of Europe, a few of whom are mentioned hereafter. 

 Armed with these, a genuine love and adaptability, success is 

 assured up to a limit, for it is not probable that all the secret 

 processes of nature can be wrested from her grasp by even the 

 greatest minds in a single lifetime. 



THE DEVELOPMENT AND PROGRESS OF THE SCIENCE OF LICHENOLOGY. 



The study of lichens was tor many years, on account of its sup- 

 posed difficulties, confined in this country to a very few persons, 

 who lived remote from each other. Thus it has a scattered and 

 little known literature, which; however meager m quantity and 

 quality (with the exception of the works of Tuckerman and 

 Willey), has proved almost inaccessible to students, or those who 

 otherwise would have become interested in a branch of botany now 

 assuming more importance among American students. There were, 

 also, other reasons why so few botanists pursued the study. Until 

 the late Professor Edward Tuckerman published his great works 

 upon American Lichens, the results of a life-time of devoted labor. 



