162 HISTORY OF BOTANY 



In the earlier editions of his textbook Sachs laid 

 stress on heterospory in his classification of the Vascular 

 Cryptogams and created three chief divisions, viz. Filices, 

 including all the fern-like plants, save Marattiaceae, which 

 he united with Ophioglossaceae to form a second group, 

 and also Equisetaceae ; these were all characterised by 

 being isosporous. To these he added two partially 

 heterosporous divisions, the so-called Rhizocarpeae 

 (Hydropteridae) and Lycopodiaceae. Later on Sachs 

 made several fundamental changes in his scheme, the 

 chief effect of which was to unite the Algae and Fungi 

 into one series, subdivided according to the nature of the 

 reproductive organs. The lowest groups he termed 

 Protophyta, which included all the forms we now call 

 Schizophyta ; the second group was the Zygosporeae 

 with isogamous reproduction ; the third the Oosporeae 

 with differentiated ova and sperms ; and the fourth the 

 Carposporeae, where the fertilised ovum gave rise to a 

 cluster of carpospores. In this last group Sachs placed 

 the Characeae. The Vascular Cryptogams were also 

 reclassified on the ground that heterospory was not a 

 sufficiently fundamental criterion on which to base the 

 larger divisions. The Rhizocarpeae were now grouped 

 with the Filicineae, and the Lycopodiaceae, Selaginel- 

 laceae, and Isoetaceae were united under the name 

 Dichotomae, from the supposed method of their 

 branching. 



In 1880 Goebel introduced a new idea into the taxonomy 

 of Vascular Cryptogams by emphasising the difference 

 in the mode of origin of the sporangium in the several 

 members of the group. He established Leptosporangiatae 

 for those in which the sporangium sprang from a single 

 cell, and Eusporangiatae for those in which the sporangium 

 sprang from a cluster of cells another illustration of 

 generalisation on the basis of a single mark. The terms 

 are still in use, but mainly in a descriptive sense. 



The next change was put forward by Eichler in 1883, 



