116 REPORT 1851. 



way out of the spore-cell in active rotation, finally emerging completely, so 

 that the moving spiral filaments are probably developed in the vesicles, while 

 these are still contained within the spore-cell. 



No actual connexion of these moving spiral filaments or spermatozoa with 

 the so-called ovules has yet been traced. 



Rhizocarpece. — Almost from the earliest period of the study of Cryptoga- 

 mous plants, attempts have been made to prove the existence of distinct sexes 

 in the Rhizocarpeas, various parts of the structure being regarded by differ- 

 ent authors as analogues of the stamens and pistils of flowering plants. Ber- 

 nard de Jussieu* went so far as to class them {Pilularia glob, and Marsilea 

 quad.) with the Monocotyledons, with Lemna, considering the large spore- 

 sacs as pistils and the small ones as stamens. 



Others have sought the male organs in the hairs upon the leaves or recep- 

 tacles f ; but the rest of the numerous authors who have written on the sub- 

 ject, have either denied tiie distinction of sexuality altogether, or are agreed 

 in considering the large spores as either ovaries or ovules, the small spores 

 as pollen-grains. Experiments have frequently been made upon the gene- 

 rative powers of the two kinds of spores. Paolo Savi:|; found that the large 

 spores of Sakinia would not germinate alone, and tlierefore he regarded the 

 small ones as anthers. Duvernoy§, on the contrary, states that he saw the 

 large spores of Salvinia germinate when separated from the small ones, and 

 therefore he did not regard the latter as anthers, but only rudiments. Bi- 

 schoff||, who minutely described the structure of the European species, said 

 that in his experiments the large spores of Salvinia germinated as well with- 

 out the small granules as with them. Agardh^ saw the large spores of Pi- 

 lularia germinate separately, but later than those united with the anthers. 

 Pietro Savi** made careful observations on the germination of the separated 

 large spores o{ Saloinia, and found them to produce a green raamilla which 

 underwent no further development ; he therefore regarded the small spores 

 as necessary for impregnation. Esprit Fabreff carefully experimented on 

 Marsilea Fabri. The separated large spores did not germinate ; they did 

 not even produce the stationary green papilla observed in Salvinia by Pietro 

 Savi. Dr. C. MvillerJ:^ found that the large spores o? Pdularia would not 

 germinate when separate from the small ones. 



The development of the spores and the germination of the larger kind in 

 Pilularia appear to have been first accurately described by Mr. Valentine §§, 

 in a paper read before the Linnasan Society in March 1 839. It is unnecessary 

 to enter into the particulars of this paper, which gives accurate statements in 

 most points, and mentions for the first time the occurrence of the cellular pa- 

 pilla upon the pro-embryo which has since been regarded as the " ovule," ana- 

 logous to that found on the pro-embryo of the other vascular Cryptogams. 



Dr.C.Muller'sllll essay appeared in 1840, and agrees in some points ; but 

 he appears to have mistaken the mode of origin of the pro- embryo. In 1843 

 Schleiden^^announced that hehadobservedaprocessof impregnation in Pilu- 

 laria, in which the small spores acted the partof pollen-grains, producing tubes 

 which entered into a cavity on the surface of the large spore or " ovule," and, 

 in accordance with his views of impregnation in general, became the embryo. 



* Hist, de I'Acad. Roy. des So. 1739 and 1740. + Micheli, Linnaeus and Hedwig 



X Biblioth. Italian, xx. § Diss, de Salv. nat. &c., 1825. 



II Nova Actaxiv. and Cryptogam Gew. part 2. 1828. ^ De Pilularia diss. 1835. 

 ** Ann. des Sc. Nat. 1837. ft Ann. des Sc. Nat. 1837. %% Flora, 1840. 



§§ Linnaean Transactions, vol. xvii. |||| Flora, 1840. 



in Grundz. der Wiss. Botanik, 1843. 



