230 



INTRODUCTION TO CEYPTOGAMIC BOTANY. 



walls became more distinctly defined, the endochrome divided 

 into two parts, one of which, in cultivated specimens at least 

 always that which was turned to the light, pushed out a little 

 root-like appendage, the divisions of the endochrome and 

 rootlets increased in number, and finally a young plant was 

 produced with a tuft of threads at its apex like those which 

 are so common on the leaves. The spermatozoids then must 

 really possess the power of impregnation, since their presence 

 is absolutely necessary to the evolution of the spores. 



218. But M. Thuret carried his researches further. By 

 mixing the spores and spermatozoids of different species, he 



Fig. 50. 



a. Antheridia of Fucus vesiculosus. 



b. Spermatozoid. 



c. Spore cases of ditto. By an error of the engraver, their attach, 

 ment is not correctly represented. 



d. One of the eight spores into which the endochrome of the spore 

 case is ultimately resolved. After Thuret. All more or less mao-nified. 



e. Spore-case and antheridia of Z)' Uroillcea Ilarveyi, magnified. From 

 a drawing by Dr. Hooker. 



foiuid that in one case he succeeded in obtaining impregnation. 

 The spores of Fucus nodosus and H. lorea refused to germi- 



