THE HIGHER CRYPTOGAMS. 261 



mation of the primary contents of the canal, and that 

 Suminski's endosperm is the embryo (1. c. p. 780). On 

 the other hand V. Mercklin's conclusion from the exami- 

 nation of the same object (' Beobachtungen am Prothallinm 

 cler Farrn-krauter,' Petersburg, 1850) was more in favour of 

 Suminski's views. V. Mercklin also thought that the young 

 archegonia were open, and believed that he had seen the 

 entrance of spermatozoa into such young archegonia, and he 

 assumed that it was not until a subsequent period that the 

 apex of the neck of the archegonium became closed 

 (1. c. p. 46). On the other hand he observed correctly the 

 bursting of the apex of the archegonium after its complete 

 formation (1. c. p. 33) as well as the presence of a globular 

 cell in the central cell (which like Scbacht and Suminski he 

 took to be an intercellular space) before the bursting of the 

 latter (1. c. p. 31). To V. Mercklin also is due the merit of 

 the first reliable observations of the entrance of the motile 

 spermatozoa into the mouth of the neck of an opened 

 archegonium (1. c. p. 46 in Jsplenium Serra). Mettenius 

 (' Beitrage zur Botanik,' Frankfurt 1850, p. 18) arrived at 

 the same results as Schacht and myself. He first pointed 

 out that the development of an archegonium from a cell of 

 the prothallium, commences with the division of this cell 

 into two cells lying underneath one another (1. c. p. 19). 



In my ' Vergleichencle Untersuchungen ' Leipzig 1851, 

 p. 81, I added to the account which I had published two 

 years before. The principal points in the literature of the 

 sexual reproduction of ferns received a further confirmation 

 from a paper of Henfrey's in the ' Transactions of the 

 Linnean Society,' vol. xxi, p. 117, 1852. In 1851 I was 

 under the impression that the germinal vesicle of ferns 

 originated by renewed cell-formation round the primary 

 nucleus of the central cell, an error which I corrected in 

 1854 (' Sitzungsberichte K.Sachs. Gesellsch. d. Wissen- 

 schaft,' Math. Phys. CI. 1854, p. 54) when reviewing my 

 first observations on the motile spermatozoa in the central 

 cell of the archegonium. In a publication which appeared 

 soon afterwards, Wigand retracted his previous contradic- 

 tions of the statements of other observers, (Botanische 

 Untersuchungen, Braunschweig, 1854, p. 151) so that 



