136 MR. HENFREY ON THE DEVELOPMENT 



It would be out of place to enter into a detailed examination of these discoveries at the 

 close of this long memoir. They are to be found in the work of Hofmeister * already 

 quoted in regard to the Ferns. I may also refer to a resumS of the present state of know- 

 ledge on these subjects, published by myself in the ' Annals of Natural History f,' for the 

 facts and general conclusions to be derived from them, and to a Report furnished to the 

 British Association in 1851, for an account of the historical development of these questions 

 during late years. 



I cannot conclude without once more directing attention to the many striking analogies 

 recently revealed between the phenomena of reproduction in plants and in animals. They 

 must excite the strongest interest in the minds of all those pursuing the study of biolo- 

 gical laws. Many of the facts rest, at present, it is true, upon the authority of but one or 

 two observers, and it can scarcely be doubted that much remains to be discovered before 

 all the details are sufficiently established. The investigation of the reproduction of Ferns 

 is the point which has been most pursued hitherto, and even here there is considerable 

 discrepancy in reference to anatomical conditions. My own observations have satisfied 

 me only after prolonged and careful study of the subject ; for Avhere we have to compare 

 successive stages in distinct preparations, and this by means of dissection of microscopic 

 structure, there are very numerous inlets for misconceptions. If I have fallen into errors, 

 I trust they may be soon detected by other observers, whom this memoir may attract to 

 similar researches. 



London, May 1852. 



DESCRIPTION OF THE PLATES. 

 Tab. XIV. 



[The specimens were in most cases self-sown plants, and moreover were often mingled before exami- 

 nation, so that I am unable to say more than that they belonged principally to an unknown Adiantum, 

 an Asplenium, Pteris serrulata, and Gymnogramma chrysophylla. Most of the stages, however, were 

 observed repeatedly in the last species. The drawings were all made in outline with the aid of the camera 

 lucida eye-piece, except in the cases of Figs. 33, 41-47, an d 75-] 



Figs. 1 & 2. Germinating spores : the second figure exhibits a radical filament. 



Figs. 3 & 4. More advanced specimens. 



Figs. 5-8. Subsequent stages, in which lateral expansion is going on. 



Fig. 9. A young prothallium, in which the peculiar obcordate form is already distinguishable. 



Fig. 10. Under surface of a young prothallium of tolerably complete form, before the thickened cushion 

 has made its appearance in the middle. 



Fig. 11. A more highly magnified view of half such a. prothallium, in which a number of antheridia exist 

 (under surface). 



Fig. 12. A young prothallium, produced by budding from the margin of an old sterile (proliferous) pro- 

 thallium (under surface). 



* See ante, page 133. t J une 1852 - 



