THE CLASSIFICATION OF PLANTS 2145 



It was not until 1880, when Koch's method of cuhivating Bacteria on sohd 

 media came into use, that an attempt was made to base a classification on 

 growth characters. Since that time, beginning with Zopf's " Die Spaltpilze", 

 published in 1883, very numerous classifications have been proposed, in 

 the endeavour to combine both sets of characteristics, namely the micro- 

 scopical form and the growth habit. No finality was reached, but among the 

 treatises produced in the attempt were several of considerable importance, 

 such as those by Lehmann and Neumann, by Alfred Fischer and by 

 Aligula. Biochemical criteria were first employed in 1905 by the Winslows 

 and this method was made the foundation of a detailed classification by 

 Orla Jensen in 1909. The investigation of Bacteria was so much in the 

 hands of medical men, to whom classification was only of minor interest, 

 that the nomenclature in the literature became very confused. To remedy 

 this the American Society of Bacteriologists appointed a committee in 19 17 

 to apply the international rules of priority and to evolve a legitimate system. 

 They proposed six orders: 



1. Eubacteriales 4. Thiobacteriales 



2. Actinomycetales 5. Myxobacteriales 



3. Chlamydobacteriales 6. Spirochaetales 



since increased to seven by the discovery of the Caulobacteria. Of these 

 orders the first is by far the largest, some of the others containing only a 

 single family. This classification was embodied and developed in succes- 

 sive editions of Bergey's " Determinative Bacteriology " and was generally 

 accepted as authoritative. In the sixth edition it was, however, greatly 

 altered in detail. It is doubtful at present whether the latest arrangement 

 will prove better than the former, though it is an improvement in some 

 respects. The orders adopted are as follows: 



I. Eubacteriales 2. Actinomycetales 



(i) Eubacteriineae 3. Chlamydobacteriales 



(ii) Caulobacteriineae 4. Myxobacteriales 



(iii) Rhodobacteriineae 5. Spirochaetales 



THE LICHENS 



Although interest in the Lichens as a source of dyes may go back as far 

 as Theophrastus, it was not until 1867 that Schwendener announced his 

 theory of their dual nature. Prior to that time attempts to classify the 

 Lichens reflected the inability of the authors to understand their true nature 

 and we need not consider them here. 



The first successful attempt to arrange the Lichens in a true natural 

 system is due to Reinke in his " Abhandlungen iiber die Flechten", pub- 

 lishedbetweeni894andi896.Thoughseveralmonographicalstudiesofcertain 

 groups of the Lichens followed, it was left to Zahlbriickner in Engler's 

 " Pflanzenfamilien " to compile a complete arrangement of the Lichens 

 along modern fines. His system may be summarized as follows: 



