448 Mr. A. Henfrey on the Reproduction of the 



archegonium soon exhibits a new development (C. fig. 4), which 

 results in the formation of an embryo, from which the new plant 

 grows up. 



The prothallium of Marsilea is developed in a similar manner, 

 and likewise produces only one archegonium ; the cells bounding 

 the canal of this do not grow out in papillae like those of Pilu- 

 laria. 



Salvinia presents some points of difference. It has been ob- 

 served that the small spores remain coherent together even after 

 their sporangium is ripe, and cannot be isolated ; but when such a 

 sporangium is compressed, in water, under the microscope, there 

 escape from its ruptured walls ellipsoid cells divided into two to 

 six chambers, in each of which subsequently appear one to four 

 minute cellules, in the interior of which are developed sperma- 

 tozoids just like those of the Ferns. 



The prothallium is produced by the large spores much in the 

 same way as in Pilularia and Salvinia, but in addition to the 

 archegonium at the apex, several others are subsequently developed 

 around it. The embryo is developed from the basal cell of the 

 archegonium, and, according to Hofmeister, never when the small 

 spores are carefully removed from contact with it. In very rare 

 cases two archegonia produce embryos. The import of the struc- 

 tures met with in Azolla is still very obscure, yet the disco- 

 veries, just referred to in the other Rhizocarpese, would lead us 

 to imagine that there is a close analogy between the two kinds of 

 organ found in that genus and those met with in Pilularia, &c. 



If I might hazard a conjecture, I should be inclined to sup- 

 pose the cellular lobes found in the upper part of the ovule-like 

 sporangium of Azolla to be the prothallium ; the c points ' seen 

 upon the cellular structure, which afterwards becomes divided 

 into the nine lobes, might possibly be archegonia ; but this is a 

 subject on which it is dangerous to venture without further exa- 

 mination of the organs. 



Fertilization op Phanerogamia. 



In no department of physiological botany have greater ad- 

 vances been made within the last few years than in the study of 

 the sexual reproduction of plants. The particulars related in the 

 last few pages sufficiently demonstrate this in reference to the 

 Cryptogamia, and it will be seen to hold of the Phanerogamia 

 from what follows. 



Most important contributions have been furnished to the 

 subject by R. Brown, Amici, Mohl, Hofmeister, Tulasne and 

 others, and I have satisfied myself of the truth of Amicus views 

 as opposed to those of Schleiden. It has proved however that 

 the subject is not so simple as was imagined, while the re- 



