242 M. Miiller on the Development of the Lycopodiacese. 



liarities of a bud, the epidermis and a formative cell-contents. 

 The only question here is, whether we are to regard this bud as 

 that of a branch, or altogether as an axillary bud like those so 

 often met with in the axils of the leaves. I consider it the bud of a 

 twig [Zweig)j which is only distinguished from the terminal bud of 

 the branch developed into the oophoridium by the circumstance 

 that the latter is a principal branch, which possibly was capable 

 of a more extensive development into branch and foliaceous or- 

 gans, while the twig which is developed into an antheridium 

 is but a small particle of such a main branch. That it is a twig, 

 appears to me to be shown by the internal structure of the fruit- 

 axis, since from its central vascular bundle are given off real 

 lateral branches to each bud (antheridia) . Yet it must be freely 

 admitted, that the vascular bundle does not actually run into the 

 peduncle of the antheridium, but terminates before reaching it, 

 and it is merely elongated cellular tissue which proceeds from the 

 vascular bundle into the peduncle (PI. IV. fig. 14). 



If now we endeavour to bring Von MohFs observations into 

 agreement with the foregoing facts, we are first opposed by the 

 statement that the sporangia are not actually situated in the axils 

 of the leaves. That is subsequently seen to be perfectly correct, 

 but does not testify against the formation of the antheridium from 

 a twig, since the simultaneously-formed antheridia and leaves also 

 simultaneously diverge from the fruit-axis, and thus it happens 

 that if a leaf be cautiously detached from the axis, the antheri- 

 dium also is removed with it, and may then always be observed 

 on the inwardly thickened base of the leaf. We have, therefore, 

 here an actual growing together of the fruit-stalk and the leaf; 

 and if Von Mohl reminds us that the shortness of the fruit -stalk 

 and the absence of it speak to the contrary in Isoetes, we have 

 here on the other hand a fruit-stalk of tolerable length, and it ap- 

 pears rather that Isoetes possesses a different structure. It would 

 be some what different with Psilotum if the antheridium were ac- 

 tually formed from the leaf. I have therefore examined this ge- 

 nus in a living state, and found that the condition is exactly the 

 same as in L. denticulatum : the earliest development of the an- 

 theridia shows their perfect independence of the leaf, and it is 

 only subsequently that the fruit-stalk contracts such union with 

 the leaf that its exceeding shortness causes it to be scarcely 

 noticed. Yet it may always be recognised as independent if we 

 trace the internal structure of the base of the sporangium in a 

 delicate longitudinal section. Here a thick vascular bundle most 

 distinctly proceeds to an internal, chambered cavity, and the 

 length of the fruit-stalk must consequently be defined by the 

 point where the bundle ends (PI. V. figs. 9 — 10). The vas- 

 cular bundle, closely examined, consists of porous vessels, like 



