io8 PERIOD IV. 



The Seientifle Investigation of the Higher Cryptogams. 

 We now resume the history of a study which down 

 to the end of the eighteenth century had yielded only 

 meagre and uncertain results (see above, pp. 85-88). 

 At the date in question it had been ascertained that the 

 spores (then called " seeds ") of ferns, and probably 

 of other cryptogams, are capable of propagating the 

 species, but no one knew precisely what part the spore 

 played in the life-history, or could explain the true 

 difference between a cryptogam and a flowering plant. 

 The great improvements in the construction of the 

 compound microscope which were effected between 

 1812 and 1830 rendered it possible to elucidate much 

 more thoroughly the structure and development of the 

 chief groups of cryptogams. The sexual reproduction 

 of algae was explored ; moving filaments (spermato- 

 zoids) were seen to enter the chambers in which 

 embryos afterwards formed ; the conjugation of similar 

 cells was observed in algae and fungi, and recognised 

 as a simple mode of sexual reproduction. The resem- 

 blance of the spermatozoids of mosses and ferns to 

 animal spermatozoa was noted, and their participation 

 in the process of fertilisation was more and more closely 

 followed until at length Hofmeister in 185 1 saw them 

 fuse with the egg-cell of a fern. Suminski, whose full 

 name, Lesczyc-Suminski, is unpronounceable by English- 

 men, had discovered (in 1848) that the prothallus of a 

 fern, which is the product of the germinated spore and 

 had been hitherto taken for the cotyledon, bears two 

 kinds ot reproductive organs, one of which liberates 

 spermatozoids, while an egg-cell is developed within 

 the other. He did not correctly describe all the details, 

 but he showed where the essential reproductive organs 



