the Anatomy of ike genus Selaginella, Spr. 79 
Farmer 1 contrasts Selaginella with Isoetes in regard to the 
structure and development of the ligule, and points out that 
in the former the ligule is multicellular in origin, whilst in the 
latter it is unicellular. He further remarks that 5 the mature 
structure of the ligule is not nearly so complete as in Isoetes , 
especially as regards its insertion. 5 My observations on the 
ligule of Selaginella scarcely bear out this view. The ligule, 
Farmer states, is developed much later in Selaginella than 
in Isoetes, 
Bower 2 gives no description of the development of the 
ligule, but in his figures illustrating the development of the 
sporangium he gives certain data worthy of comment : his 
Fig. 79 (PL 47) shows a primary stage in the development of 
the ligule of 5 . Martensii , where two shaded cells (in longi- 
tudinal section) indicate its point of origin, whilst Figs. 84, 85, 
86, 87, and 89 illustrate stages in the development of the 
ligule of 5 . spinosa, to which I shall have occasion to refer 
later. Professor Bower has been so kind as to place his pre- 
parations at my disposal for comparison with my own, and 
I may say that they fully bear out his figures. 
Campbell 3 , in his recent work on Mosses and Ferns, gives 
a brief reference to the ligule in S. Kraussiana , and speaks of 
it as ‘ much constricted at the point where it joins the leaf. 5 
His figure (Fig. 261), moreover, shows the sheathing-cells of 
the glossopodium not continuous with the epidermal-cells, 
but quite outside them. 
It will be seen from this short summary that our know- 
ledge of the variations in the adult form of the ligule and its 
comparative development in different species is, to say the 
least, meagre ; whilst we have conflicting accounts of its mode 
of development in the works of Pfeffer and of Hofmeister, 
the former describing it as arising from one row of cells in 
►S. Martensii [‘ wie bei diesen ensteht am Grunde der Innen- 
seite der Kotyledonen eine Ligula, an deren Bildung ich immer 
1 On Isoetes lacustris , L. Annals of Botany, Vol. v, 1890. 
2 Studies on the Morphology of spore-producing Members. Phil. Trans. 1894. 
3 The Structure and Development of Mosses and Ferns. Macmillan & Co. 1895. 
