12 



MARSILEACE.E. 



[ACROGENS. 



1 ig. L. 



pollen " collect about the nipple at the surface of the water, after which the " ovules " 

 fall to the bottom, where, at the end of seven or eight days germination commences. 

 These observations, however, require to be repeated: for Braun {Flora, 1839, p. 297,) 

 and Griffith each regards both sorts of bodies as spoiniles. Fabre's experiment calls to 

 mind those of Professor Savi of Pisa, upon Salvinia, 

 another plant of this Order. He put into different ves- 

 sels, 1st, the seeds alone ; 2d, the male globules alone ; 

 and 3d, both mixed. In the first two vessels nothing ap- 

 peared ; in the 3d, the seeds rose to the surface of the 

 water and fully developed. But Duveraey has since 

 published a dissertation upon this plant, in wliich he 

 states that, having repeated the experiments of Savi, he 

 has not obtamed the same results, and that the seeds, 

 when separated from the supposed male organs, developed 

 perfectly. 



The structure of Pi- 

 lularia is analogous. 

 From the very correct 

 and careful observa- 

 tions of Valentine, 

 J\ II I'W^ IfA (^"^^.^?'«ws- 18.483,) 

 ' y i ^^^"^ M\l ^* ^^^^ apparently been 

 — // II W v\v) proved, that the so- 



called anthers of that 

 plant are, as I for- 

 merly suggested, no- 

 thing but abortive spores. 



Following Jussieu, Salvmia and Azolla were sepa- 

 rated in the last edition of this work as a distinct 

 Natural Order, a view that Endlicher has since taken. 

 But upon a full consideration of the structm*e of these 

 plants, or of what is kno^Ti of it, it does not appear 

 to justify the separation. Like Pilularia and Marsilea, 

 they have two distinct kinds of rej^roductive bodies 

 enclosed in involucres, and that seems to be the main 

 feature by wliich Pepperworts are known as an Order 

 from Lycopodiaceae. For the same reason it appears 

 better to combme \\'ith them Isoetes, instead of re- 

 garding that too as the type of still another Order. 

 ^'Ii*. Griffith does not include Isoetes among these 

 plants ; but I camiot assent to the propriety of ei'ect- 

 ing evei'y genus m tliis curious Order into a Suborder. 

 The genera Sahinia and Azolla have been the sub- 

 ject of some elaborate observations by Mr. Griffith, 

 (Calcutta Journal, vol. v.), who elevates each into a 

 Suborder, and throws an entu'ely new light upon 

 their stnicture. He regards them as haiiug true 

 sexes, the male being certain necklace-shaped threads 

 fomid at an early stage, in contact with what he de- 

 nominates an orthotropous o^^llum. But strange to 

 say, this so called o\nilum, instead of gi\Tng bu'tli to 

 an embryo, becomes the parent of reproductive bodies 



of two totally different kmds, ha^dng not even the smallest resemblance the one to the 

 other, although the matrix out of which they are evolved is identical at an eai-ly period 

 of the organisation. I regi-et that Mr. Griffith's most curious memoii' only reached me 

 as tliis sheet was going to press, so that it was impossible to have cuts prepared to 

 illustrate his observations, for wliich the reader is refeiTed to the work above quoted. 

 All I can do is to give in a note the substance of his descriptions of Salvmia and 

 Azolla.* 



* Salvinia verticillata.— Male organs? articulated hairs on the stalks of the o\Tila • each joint con- 

 taining a nucleus and a brownish fluid ; Ovula nearly sessUe, concealed by the roots, and partly covered 



Fig. L.— Marsilea pubescens in different states of germination; advancing from 1. the spore, up to 4. 

 the perfect young plant. 



Fig. LI.-l. Pilularia globulifera ; 2. spore-case, natural size, bursting ; 3. the same younger and 

 magniiied ; 4. a section of the spore-case, showing the large and small spores, (after Valentine). 



