1883-84.] Edinburgh Naturalists' Field Club. 139 



retain the better known nomenclature, and continue to term it Sela- 

 ginella selaginoides. It is pretty widely distrilnited in Britain, from 

 AVales northwards, and may be found on the Pentland and Lomond 

 hills, as well as on most of our Higldand hills, growing in boggy 

 ground. 



As noted above, we have numerous exotic Selaginellas growing in 

 greenhouses, a few of these being perfectly hardy, so that this is a 

 class of i^lants which can always be examined in the living state. 

 Some forms, as S. Poulterii, S. helvetica, and S. Kraussiana Avith 

 its varieties aurea and argentea, grow very luxuriantlj^, and form a 

 lovely carpeting for Ferns, under a bell-glass or in a AVardian case. 

 The stem of the Selaginellie is almost always flat and slender, 

 branching abundantly. Its structural form is somewhat akin to 

 that of Ferns, in so far as that tliere is no axial cylinder, and the 

 vascular tissue is arranged in separate bundles, the form varying in 

 the different species. The leaves are small, often of two sizes, and, 

 like the Lycopods, have only one fibro-vascular bundle penetrating 

 them — viz., the midrib. At the apex the leaves are altered to form 

 a spike, which carries the fructification — the two kinds of spores 

 already mentioned. The macrospores, or female spores, are generally 

 four in number, but sometimes two or eight are found ; while the 

 microsjjores, or male spores, are numerous. The former are borne at 

 the base of the fertile spike, while the latter are found on the dipper 

 part. Both kinds of spores develop a small rudimentary prothallus 

 within the spore-case, before the spores are shed. It is extremely 

 interesting to trace the connection between flowerless and flowering 

 plants as represented by the Selaginellse. Indeed they seem to form, 

 in a marked degree, the connecting link between these two great 

 classes of plants, joining on the higher Cryptogams in the one class 

 to the lower Gymnosperms in the other. This is the more evident 

 when we consider that the antheridia and archegonia respectively of 

 the one have their analogue in the pollen-grains and the embryo-sac 

 and ovule of the other. It is true that the lihizocarps, including the 

 aquatic or sub-aquatic Salvinia and Marsilia, Avith Isoetes and our 

 native Pillwort, also possess two kinds of spores ; but these Vascular 

 Cryptogams are all less highly developed in their structure than the 

 SelagineUaj. Again, attached to the embryo of flowering-plants there 

 is always present what is termed a suspensor, from which tlie first 

 root proceeds. Among Cryptogams, Selaginellas alone are furnished 

 with this body. A good illustration is thus supplied of the dictum 

 of Linnreus, "l^atura non saltus facit"; for here we find the members 

 of the less highly developed class of plants which are at the top of 

 the scale in that class beginning to anticipate, as it were, the repro- 

 ductive structure and mode of growth of the lowlier members of the 

 other and higher class. 



Unlike the embryo of Lycopodium, that of Selaginella lias been 



