M. Miiller on the Development of the Lycopodiaceae. 243 



that which proceeds into the leaf. That the sporangium of Psi- 

 lotum however is chambered, is not to be explained, as Von Mohl 

 believes, as resulting from a growing together of several spo- 

 rangia, but by the fact that — as the course of development shows 

 — the sporangium is always simple in the youngest stage, and 

 the several partitions are formed in its interior subsequently, the 

 number often amounting to four. The partitions are formed of 

 parenchymatous cellular tissue, which ramifies in the interior and 

 consists of enlarged cells. These facts I have observed with the 

 greatest certainty, although I cannot declare the law by which the 

 ramification of these layers of cells is governed, and why their cells 

 do not rather become mother-cells for the spores. That the fruit 

 of Psilotum is one-, two-, three- or four-chambered, indicates, 

 from what has already been said of it, that a growing together of 

 leaves or sporangia is not to be thought of here. The inconstancy 

 is too great to admit of our believing, that several sporangia can 

 be developed freely in one axil and so grow together. Here in 

 Psilotum however it would be more pardonable than in any other 

 case, to explain the formation of the sporangium by the growing 

 together of carpels, since in a tolerably perfect sporangium a 

 pretty distinct furrow runs over each globular protuberance 

 {Hilgel), which may easily lead an observer to suppose that it is 

 formed of leaves grown together. In this genus indeed a complete 

 history of the development might become in the highest degree 

 interesting. The structure of the antheridium appears to me to 

 be still more clearly evident in Tmesipteris than in Psilotum, at 

 least from the dried specimens I was able to examine in the Royal 

 Herbarium at Schoneberg near Berlin ; for in these the fruit- 

 stalk was often developed to a considerable length and projected 

 beyond the leaf. In fact, we have here as in Psilotum a simul- 

 taneous formation of sporangia and leaves, so that it is impos- 

 sible that the former can be composed of the latter, as in such 

 case the sporangia must clearly be formed subsequently. 



H. von Mohl also opposes to Bischofi'^s view, the formation of 

 the spores in the same manner as pollen-grains, &c., which I have 

 already refered to. This cannot be made to contradict my opi- 

 nion — in fact, it even does not once touch BischofF^s. For where- 

 soever formative substance is present, there cells may be formed. 

 These formed, and a sufficient quantity of the formative matter 

 still present, new cells again may be formed within the first, the 

 mother-cells, and the second generation become perfect simple 

 cells which we then call spores. 



Regarding Von MohFs and Bischoff's opinions therefore, I 

 hope that I have succeeded in displaying in a convincing man- 

 ner, a different theory of the course of development of the anthe- 

 ridia. As to Schleiden's so very definitely stated views, how- 



