1 66 BACTERIA IiX RELATION TO PLANT DISEASES. 



able condition. The organism was a short rod, mukiplying by cross-septation, 

 possibh' also by means of spores, colorless, sluggishly motile, moving, it is said, by 

 means of one polar flagellum, and occurring abundantly in water containing rotten 

 \'egetation, where bacteria would be likelv to abound. It should also be noted that 

 it did not take up colored particles, such as indigo or carmine, when placed in water 

 containing these substances. If the word Bacterium is used, it should be in con- 

 formit)' to these facts, or supposed facts, and ma)- be so used, I think, until they are 

 shown to be erroneous. 



The matter is simplified, however, if we start with Colin's use of the word 

 Bacterium in the year 1872. The Bacterium of Colm is a certain Bacterium 

 termo. While we are not able to tie down Cohn's use of this name to a particular 

 species, it appears that we can do it quite definitely to a group of morphologically 

 similar species. Much discredit has been thrown on Bacterium termo in modern 

 times, and it lias been left out of many classifications. However, if one examines 

 into the matter, there is no reasonable douljt as to what Cohn had in mind. His 

 Bacterium termo was a small schizomycetous organism capable of growing freely 

 in Cohn's nutrient solution, containing acid potassium phosphate and ammonium 

 tartrate. It produced therein short rods (single, in pairs, or fours joined end to end) 

 and roundish-lobed (kugelige-traubige) white zooglcea;, together with a greenish 

 fluorescence. This is Cohn's statement and de Bary's. It did not 

 J^^^'^^^ri appear in boiled fluids, /. 6\, was destitute of endospores (Cohn), 

 P^'t^^^^i*!^ and the motile rods were killed by a short exposure to 58° C. 

 ^ ''itf^!t^"Si^ (Schroeter). In other words, it was a non-sporiferous green- 

 T:iJ^;^'\' fluorescent organism possessed of a single polar flagellum, or, in 

 3^?^^I''^i-'i' some cases perhaps, provided with paired or triple polar flagella. 

 M»!tii*=V..»«-9-i jjT .^,^,g start with Cohn's classification in the year 1872, we may 

 Fis 137* keep the name Bacterium for schizomycetous organisms of this 



t)pe, and at the same time we shall not be doing any violence to 

 the older use of the word by Ehrenberg, who figures and describes this kind of an 

 organism. This the writer proposes to do, substituting Bacterium (Cohn emend.) 

 for Pseudonionas Migula and for more recent names proposed by others. Cohn's 

 description, be it understood, is worthless for the most part, but his name Bacterium 

 {B. termo) is u.sable because it can he attached to a definite kind 0/ organism. To show 

 that Cohn's use of tliis word and the writer's use of it do not conflict with former 

 usage, IChrenberg's descriptions and figures of Bacterium are here reproduced from 

 the expensi\e and not readily accessible publications in which they appeared. 



The organism described as I^actcrium triloculare by Ehrenberg is shown in 

 figs. 137 and 138, and Ehrenberg's account is summarized as follows: 



The genus liacterium was founded b}- C. r>. p^hrenberg in 1828, and was 

 characterized b}- him in the Symbokc PhysiccX-, Animalia evertebrata. The book in 

 which tliis description occin"s is an unpaged folio. On the second page of the text 

 proper, in a list of species found "In Oasi Io\is Hammonis Siwae" this genus 



*FiG. 137. — Baclcriuiii InliHuhirc. From ]{liiviilicrg's Synilicil.L- Pliysic:c. Animalia evertebrata. 

 Decas prima. Berlin, 1828. Plate 11, fig. 6. 



