82 M. Miiller on the Germination 0/ Isoetes lacustris. 



that some conclusion might be drawn as to the degree of their 

 relationship. 



The second reason which especially attracted me to the inves- 

 tigation of this subject was the peculiarity of the root- stock, first 

 observed and described by H. v. Mohl, on which the youngest 

 roots, contrary to the custom in all other vascular plants, deve- 

 lope out of the centre of the stem in a deep furrow, while the 

 rootlets occurring on the outer periphery of the root-stock are 

 the very oldest. It might be expected that the history of the 

 development would give some information as to this circum- 

 stance; indeed it must be admitted that without a thorough know- 

 ledge of it, no safe opinion can be formed of the nature of the 

 matter. Whether the following complete account of the deve- 

 lopment up to a tolerably perfect condition of the germ is suffi- 

 cient for the above purpose, will subsequently be seen. 



There was yet a third reason which rendered the whole inves- 

 tigation highly desirable to me ; namely the wish to examine 

 how the earliest formation of the embryo took place in an 

 asexual plant, how it was brought about. It will be readily con- 

 ceded here also, that this parallel is extremely well fitted to 

 throw light upon the formation of the embryo in both classes of 

 plants. Whether and how far the following history of deve- 

 lopment will allow of the parallel being perfectly drawn, will 

 hereafter be evident in the course of the exposition. I think that 

 at this moment we are in the utmost need of an investigation 

 which shall show the — I might call it uteral — formation of the 

 embryo in an asexual plant, where consequently there is no 

 question about pollen-tubes. I think so the more that it will 

 not be long before two parties stand opposed to each other, one 

 ranged under the banner of Schleiden, the other of Amici. Sela- 

 ginella, and still better Isoetes, on account of the readier germi- 

 nation, perfectly admit of such an investigation, and the poor 

 botanist who has looked around him so much for analogies, has 

 really much reason to be earnestly thankful for the creation of 

 the Lycopodiacese, for I know of no other family in which this 

 again occurs. 



These three reasons determined me to an investigation of a com- 

 plete course of development of Isoetes lacustris. I would willingly 

 — as indeed I much wished — have given a further account of the 

 whole course of development of this plant, but the air of the 

 chamber affected all my hundreds of germinating plants, which 

 I the more regret since my time is now too much taken up with 

 other botanical matters to allow of my calculating on returning 

 very soon to this subject. It was also part of my plan to add the 

 earliest stages of the development of the Selaginellce — which in 

 my earlier researches I neglected, or rather did not discover. I 



