440 History of the Sexual Theory. [BOOK in. 



covery to systematic botany has been already noticed. The 

 conception of these relations developed by Hofmeister was not 

 less important to the doctrine of the sexuality of plants ; it 

 swept away at one stroke all the old false analogies between 

 Phanerogams and Cryptogams and brought to light the real 

 agreement ; Hofmeister had detected in the archegonium of 

 the Cryptogams the body which is developed there, as in the 

 ovule of the Phanerogams, into an embryo after fertilisation, 

 namely the germinal vesicle or egg-cell. Here was the point of 

 departure for all further systematic comparison in the sexual 

 propagation of Cryptogams and Phanerogams. All beside was 

 of secondary importance, even the fact, that the fertilisation 

 of the egg-cell in the Cryptogams is not effected by a pollen- 

 tube, but by spermatozoids. It was now easy to show the 

 corresponding relations of generation in the other cases which 

 Hofmeister had not yet observed. 



Hofmeister's statements and conclusions respecting Sela- 

 ginella and Isoetes were confirmed and some additions made 

 to them by Mettenius in 1850, and in 1851 appeared Hof- 

 meister's exhaustive work ' Vergleichende Untersuchungen,' 

 in which the mode of production of the embryo in Coniferae 

 was represented as an intermediate form between those of 

 Phanerogams and Cryptogams. Further contributions were 

 made to the knowledge of the subject ; Henfrey confirmed 

 Hofmeister's results in the case of Ferns ; Hofmeister him- 

 self and Milde observed in 1852 the history of fertilisation 

 in Equisetaceae, and the former supplied at the same time a 

 more complete account of the development of Isoetes; in 1855 

 he described the decisive points in Botrychium and Mettenius 

 in 1856 those in Ophioglossum. 



The processes of development before and after fertilisation 

 were now cleared up by all these discoveries, but the direct 

 observation of the act of fertilisation was still wanting. 

 Hofmeister ('Flora,' 1857, p. 122) describes the state of affairs 

 in the following terms : ' While numerous investigations had 



