r- 



LECTURE V. 



in the richness in species of the Fungi, and in the great variety of their modes 

 of life. 



In this condensed treatment of comparative organography, I have aimed 

 essentially at bringing forward only those points which may serve for the under- 

 standing of subsequent general physiological expositions. To this end we have 

 regarded the different parts of plants simply as organs, i. e. as instruments for definite 

 physiological functions; and in particular, only those which, in contrast to the Re- 

 productive organs, have been distinguished 

 as the Vegetative organs. This physio- 

 logical treatment of organography, hitherto 

 unduly repressed in Botany under the sway 

 of the morphological school, is moreover 

 by no means intended to exclude the purely 

 formal comparison, as it has hitherto been 

 conducted under the name of morphology; 

 its effect on the latter is only to be that 

 of explaining and enlightening. That the 

 comparison of organic forms from purely 

 physiological points of view, which are ex- 

 clusively concerned with the functions of 

 the organs, can exhaust one side only of 

 the subject, and that, besides the fimctional 

 signification of the organs, phylogenetic re- 

 lations also exist, which, quite independently 

 of the mode of life of organisms, concern 

 their relationship and their descent, requires 

 in our time no proof The whole of syste- 

 matic botany and morphology, so far as 

 they have any meaning at all, have to do 

 exclusively with this ; and it is just because 

 this morphological and phylogenetic mode 

 of consideration of plants has always pre- 

 vailed in Botany, and now threatens to 

 overgrow every other interest in plants, 

 that I have considered it to the purpose to 

 obtain, by means of the preceding lectures, a more fitting basis for our physio- 

 logical considerations. 



Only this one point ,1 would yet emphasise here. According to my view, 

 progress in the department of Botany lies in the physiological direction; and 

 sooner or later, starting ffsm physiological points of view, we shall also come 

 to understand the proper morphological hereditary properties of the organs and 

 the causes of their variations. The purely, formal relations of organisms among 

 themselves also, chiefly disclosed by the history of development, must sooner or 

 later be expressed as the effects of physiological causes which can be definitely stated ■ 



Fig. •jo.—Agarictis campesiris. A shows the mycelium 

 (»t) beset with fructification ; /—^development of the fructi- 

 fication (natural size). 



