88 



The Naturalist. 



In ferns, wlien the spores germinate the outer coat of the spore 

 bursts, and the inner coat is protruded, and by frequent cell division 

 expands into a thin Marcliautia-like structure called Prothallus. On 

 the lower surface of this prothallus, after a while, minute papillse-like 

 bodies are formed, seeming somewhat similar when seen with a low 

 magnifying power, but found to be very different when more highly 

 magnified. These are the organs of reproduction, and are termed the 

 Antheridia and Archegofiia. 



The antherid'm, or male organs of reproduction, are somewhat 

 spherical bodies, and consist of cellular papillge, having a central 

 cavity containing free cellules ; each of these free cellules when more 

 fully matured contains a small ciliated spiral body, which is called the 

 8permatozoid or Anther ozoid. 



The archegonia, or female organs of reproduction, are larger, con- 

 sist also of cellular papillae, and when very young are somewhat 

 dome shaped, with an apiculus or neck. In the centre of this neck 

 later on, may be traced a closed canal leading to a central nucleated 

 cell, which is embedded in the substance of the prothallus, but before 

 the complete formation of the canal I have mentioned a secondary 

 free nucleus is formed in the central cell of the arcJiegonium. This is 

 the germinal vesicle. 



After a while the closed canal opens externally by the absorption 

 of some of the cells bounding its upper part, thus allowing a free 

 passage from without into the interior of the nucleated cell, and 

 according to the observations of Hofmeister, the spermatozoids of the 

 antheridia pass down this open canal and ultimately reach the interior 

 of the central nucleated cell. Here they sport actively around the 

 germinal vesicle, and by their agency the fertilization of this cell is 

 brought about. The canal now again closes, and the germinal 

 vesicle, by frequent cell division, increases in size, forming at length 

 the bud of the future plant, and from this bud the fern plant, bearing 

 its leafy fronds, and on these in due time the sori, or fruit, is 

 developed. 



I have not attempted here to give an account of the devolopment 

 of the sori and spores ; the subject is complex, and would require a 

 special preparation of slides for its proper illustration. Nor have I 

 attempted to give a detailed account of the development of ferns 

 from buds, or gemma. I have merely treated of the normal develop- 

 ment of these plants. 



When the spores of mosses germinate, they usually give rise to a 



