CHAP, i.] Sexuality in Cryptogams. 443 



proved decisively that a real intermixture takes place of the 

 male and female elements of fertilisation ; this important fact 

 was confirmed by De Bary in the same year. 



Now that it was once established, that fertilisation in 

 Cryptogams consists in the blending together of two naked 

 bodies of protoplasm, the spermatozoid and the egg-cell, it 

 was reasonable to conclude that conjugation in Spirogyra and 

 generally in Conjugatae, was an act of fertilisation, only in this 

 case the two fertilisation-elements are not of different size 

 and shape, but similar in appearance. To this conclusion De 

 Bary arrived in 1858 in his monograph of the Conjugatae. 

 This extension of the idea of fertilisation to cases in which the 

 uniting cells are to outward appearance alike, was of special 

 value to the theory of sexuality, as was seen in the sequel, 

 when other forms of fertilisation were observed which made -it 

 necessary still further to extend the idea of sexuality. In 1858 

 Pringsheim discovered arrangements for fertilisation in another 

 group of Algae, the Saprolegnieae, which to outward appearance 

 at least departed widely from those hitherto known in the 

 lower plants. 



Thus between the years 1850 and 1860 a number of funda- 

 mental facts were discovered, and were afterwards confirmed 

 and extended by fresh observations in the course of the follow- 

 ing years. It does not fall within the limits of this work to 

 notice the many discoveries that were made in this part of 

 botanical science after 1860 ; we will only remark, that between 

 1860 and 1870 the processes of fructification were observed 

 by Thuret and Bornet in Florideae, and especially by De 

 Bary and his pupils in Fungi, in some of which very peculiar 

 forms were brought to light. No doubt any longer exists that 

 difference of sex prevails generally in the Thallophytes also, 

 though it is still an open question, whether it may not be 

 wanting in some of the very simplest and smallest kinds. 



One of the most important results of these investigations 

 is obviously the striking resemblance between many of 



