43 8 History of the Sexual Theory. [BOOK HI. 



lated, and towards 1845 ** began to be possible by critical 

 examination of them to arrive at something like a clearer 

 understanding of this part of botany. The majority of 

 botanists readily accepted Schmidel's and Hedwig's opinion 

 with respect to the Mosses; Vaucher had as early as 1803 

 maintained that the long-known conjugation of Spirogyra was a 

 sexual act; Ehrenberg observed in 1820 the conjugation of a 

 Mould, Syzygites ; Bischoff and Mirbel explained the organ- 

 isation of the antheridia of the Liverworts in 1845, while Nees 

 von Esenbeck saw the spermatozoids of Sphagnum in 1822 

 and Bischoff those of Chara in 1828, though they were at first 

 taken for Infusoria, an opinion maintained by Unger as late as 

 1834. But it was Unger 1 , who in 1837, after careful study of 

 the spermatozoids of the Mosses in 1837, declared them to be 

 the male organs of fertilisation ; in 1844 Nageli discovered 

 corresponding forms on the prothallium of Ferns, which had 

 till then been called a cotyledon, and in 1846 the spermatozoids 

 of Pilularia, the products of the small spores which Schleiden 

 had explained to be the pollen-grains of that plant. 



These facts were of the highest importance, but little was to 

 be made of them as long as the female organ in the plants in 

 question, the Mosses excepted, was unknown, and meanwhile 

 it was only the resemblance between vegetable and animal 

 spermatozoids which led to the conjecture, that the one had 

 the same sexual significance as the other. 



Light was suddenly thrown upon the subject, when Count 

 Lesczyc-Suminsky discovered in 1848 on the supposed cotyledon 

 (prothallium) of Ferns both the antheridia and the peculiar 

 organs, inside which the embryo or young fern is formed. 

 Though the statements respecting the structure and develop- 

 ment of these female organs and of the embryo were inaccurate 

 in some important points, yet the place was now indicated 



1 The authorities for these statements are collected by Hofmeister in 

 'Flora,' 1857, p. 120, etc. 



