49 



and (2) Specific diseases. The first includes :— La gangrene— le desseche- 

 ment — la surabondance de sue — le branchage excess! f — une espece de galle, 

 qui manche I'ecorce. In the second main group we find: — Le dessechement 

 des racines — la separation de leur ecorce — la grosseur excessive des racines. 

 qui retienent tout le sue de la plante — les excroissances — les coups et les 

 biessures. It is evident from this division of closely related phenomena that 

 the author had not fully mastered his material. 



Eysfarth's^ system gives a classification which the layman easily 

 grasps. It uses as its basis the different periods of the plant's Hfe. In 

 the first class are the diseases of the period of germination ; in the second, 

 those of the actual vegetative period and in the third class, the disturbances 

 of the sexual period. Under each class are discussed the influences of 

 weather extremes, injuries due to animals and other wounds. In this book 

 there is also a chapter "a rubigine aut pruina." The thoroughness of the 

 classification shows that the author had well worked out his material. 



Adanson- returns to Tournefort's division since he sets up as his 

 first main group the "maladies dues a des causes externes," and as the 

 second, the "maladies dues a des causes internes." Even the introduction 

 shows the advance in microscopic investigation and the increased attention 

 paid to parasitic fungi ; under the first main group, the dififerent chapters 

 take up, for example, Le givre ou Jivre (Erysiphe Fabricii) — la rouille 

 kgu(f[(nrj Theophr. (Rubigo) — le charbon (Ustilago) — la pourriture (Caries 

 Fabr.) etc. 



Adanson often uses the terminology of Fabricius who probably had 

 published his studies in separate treatises before his classification had ap- 

 peared as a whole, for his complete classification did not appear until 1/74^'. 



Fabricius certainly based his views on his own observations. This is 

 less noticeable in the formation of the main groups than in the sub-divisions 

 of the dififerent chapters, in which a classification of the cases according to 

 their dififerent causes has been stated, even when the external appear- 

 ance was similar. Thus, for example, we find in the first main group : — 

 "Vf rugtbargiorende Sygdomme," i. e. the disturbances leading to sterility ; 

 a section "Dovhed" which may be translated by etiolation or the yellows. 

 This is divided into D. af Regn, af Kulde, af Rog etc. His observation that, 

 besides rain, cold and other factors, "yellows" may be produced by smoke 

 is also worth notice. In the second main group, "Udtaerende Sygd," i.e. the at- 

 rophias, there is found under the section "Quaelelse," etiolation from "stedets 

 Indslutning" (too close planting), from "paa Lys" (lack of light) and from 

 clinging plants and insect injuries. x\nother group is separated from these 

 phenomena, — ^"Taering" (Tabes, Jaunisse in Adanson) where the yellowing 

 is due to insufificient nutritive substances, unsuitable soil conditions, ex- 



1 Christ. Sigismund Eysfarth, Diss, pliys. de morbis plantarum. Lipsiae 1723. 4 . 



^ Adanson, Sur les maladies des plantes; in "Families des Plantes." Vol. I, p. 42. 

 1763. 8°. 



3 Forsfig til en Af handling- om Planternes Sygdomme ved Joh. Christ Fabricius; 

 ind der kongelige Norske Videnakataers Selskab skrifter femte Deel. Kjobenh. 1774. 

 Sid. 431-492. 



