142 Transactions of the [Sess. 



separated by medullary rays, growing by additions to their exterior 

 margins. In fact, if this description is a correct one, we have here a 

 Cryptogam exhibiting a true exogenous structure. On this point, 

 however, a tough battle has been waged. Prof. Williamson and 

 others hold to tliis growth being really of an exogenous nature ; while 

 the opposing party, headed by Mr Carruthers, maintain that there is 

 no true exogenous growth, and that the so-called wedges are but the 

 result of the fibro-vascular bundles proceeding from the central axis 

 to the branches and leaves. The final decision, therefore, may be 

 said to be still in abeyance.-*- 



When we consider the fragmentary nature of the material with 

 which the pal^obotanist has in most cases to deal, it is not surprising 

 that the results are often unsatisfactory. Thus, the stem, leaves, and 

 fruit of one and the same plant have been each assigned to different 

 genera. The Calamites were originally figured upside-down, with the 

 roots in the air and doing duty for branches. Stigmaria was for some 

 time a generic designation, but now it has been satisfactorily proved 

 that what were so termed are but the rootlets of Sigillaria and Lepi- 

 dodendra. The affinities of the fossil Sigillaria have not yet been 

 decided. Principal Dawson of Montreal considers them to be allied 

 to the Cycads, while Mr Carruthers holds them, with some show of 

 reason, to be Cryptogamic and Lycopodiaceous. What were really 

 the varied forms of the ancient " Club-mosses," or how great their 

 number, it is impossible to fix with any degree of certainty. Indeed 

 it is remarkable how much original work yet remains to be done in 

 this special domain of science, although so many patient and enthusi- 

 astic investigators have already occupied the field. Every discovery 

 helps on the cause of truth, and adds to our stores of information ; 

 and Nature has many secrets yet locked up in her breast, ready to be 

 yielded up to the true knight-errant. In this quest some of our 

 members have already been ardently engaged, and we may hope to 

 hear the results of their labours at a future time. Meanwhile, if I 

 have only been successful in the much humbler task of drawing 

 attention to this subject, and of showing that our lowly Club-mosses 

 have a most interesting life-history, stretching far back into the past 

 ages, then these remarks have not missed their purj)0se. 



[Besides plant-specimens and specimens of fossil Lepidodendra and Stro- 

 bili, the following preparations were shown under the microscope in illustra- 

 tion of the above — viz., (1) trans, sect, of Lycopodium stem ; (2) trans, sect, of 

 Selaginella stem ; (3) longit. sect, of do. ; (4) Sporangia of Lj^copodium ; 

 (5) Sporangia of Selaginella ; (6) trans, sect, of (fossil) Lepidodendron stem.] 



1 In connection with this controverted subject, see 'Trans. Bot. Soc.,' vol. 

 viii., "On the Structure and Affinities of Lepidodendron and Calamites," by 

 Mr Wm. Carruthers ; and Prof. Williamson on Fossil Lepidodendron, in 

 Sachs' ' Text-Book of Botany,' 2d ed., pp. 4S4, 485. 



