144 THE PHENOMENON OF 



spores. Two kinds of thick-coated and resting spores, 

 niacrospores and microspores, which are both found in 

 the same way, in fours in mother-cells, occur, lastly, in 

 many Lycopodiacete,* in the allied genus Isoetes,\ and in 

 the genera of the Rhizocarpese, Marsilia, Pilularia, and 

 Salvinia. In the examples last named we have advanced 

 very far beyond the original simplicity of the vegetable 

 structure which we had before us in the first examples ; 

 they only admit of citation here, in so far that they like- 

 wise exhibit essentially similar generative series of mother- 

 cells, and finally go out into distinction of fructification 

 cells, j 



In the higher groups of the Vegetable kingdom, the 

 difierence of the fructification-cells is preceded by a still 

 more important difference of the vegetative generations of 

 cells. The distinctly qualitatively differenced reproductive 

 cells (fertilizing-cells and germ -cells) formthe conclusion not 

 of similar, but of unlike series of generations of cells, and, 

 moreover, not of all,but only of certain series of generations, 

 while a still greater number of series attain their purpose 

 and destination within the vegetative organism, without 

 arriving at fructification in the last generation. While 

 in the lowest plants, all vegetative cells, as mere repe- 

 titions of the same thing, belong to one rank, in the 

 higher the cells divide, in the coui'se of the generations, 

 into different ranks, by which the organism is completed 

 on a different side, and through which is caused a inore 

 necessary coherence and more intimate combination than 



* Goppert concludes that both the small and large spores are capable of 

 germination, from observation of two different forms of the young plants in 

 Selaginella denticulata. ('Uebersicht der Arbeiten der Sohles. Ges. fur 

 Vaterl. Cultur.,' 1845, p. 129.) (Proved incorrect.— A.. H.) 



f According to a recent note in a letter from Dr. Mettenius (Nov. 1844), 

 spermatozoids are developed in the small spores during the germination of 

 the large spores, vrhich confirms the analogous observation of Nageli on 

 Pilularia. ('Zeitschr,,' 1846, 188.) 



X (On this subject, much di;veloped since the above was written, consult 

 the Report on the Higher Cryptogamia, by A. Henfrey, in the 'Annals of 

 Nat. History,' 2d ser., ix, 441, which also gives most of the new literature 

 of this subject. — A. H.) 



