PREFACE. 



This paper was prepared for publication in August, 1897, at which 

 time I had secured characteristic infections and had worked out many 

 of the cultural and other characters given in the following pages. 

 The fact that I had not again produced the disease with germs isolated 

 from mj^ first series of infected plants, the further fact that I could 

 not satisfactorily explain the meager growth of the parasite in the 

 host plant, and on steamed j)otato and the other culture media which 

 I had used, and, finally, a shadow of doubt concerning the accuracy 

 of two or three other observations, induced me to withhold tlie paper 

 and repeat the experiments. In the time which has intervened I have 

 gone over nearly or quite all of the experiments detailed in the origi- 

 nal paper, without, however, discovering any serious errors. During 

 this time reinfections have been secured, the reason for the feeble 

 parasitism lias been discovered, and a number of other interesting 

 facts have been brought to light, so that the long delay of publication 

 has not ])een without its comiDensations. 



Throughout this study numerous comparisons have been made 

 with two other yellow bacteria, Pseudomonas campestris and Ps. 

 phaseoU, and occasional mention has been made of them in this paper, 

 both being plant parasites. Occasional comparisons have also been 

 made with other bacteria, especially with Ps. Stewarti. The leading 

 cultural characters of the hyacinth organism are mentioned in the 

 synopsis at the end of this paper, but it has been decided to relegate 

 an account of the numerous experiments on which these conclusions 

 rest to a second bulletin, which is now ready for publication and in 

 which they will be discussed in connection with the cultural pecu- 

 liarities of the other yellow species of Pseudomonas here mentioned. 



It is too much to hope that this bulletin is entirely free from mis- 

 takes. Nevertheless great pains have been taken to make it trust- 

 woi'thy, all of the experiments having been performed in duplicate, 

 and iiearlj^ all of them having been repeated several times on differ- 

 ent occasions to eliminate unsuspected sources of error. 



Some brief statements respecting the morphology and physiology of 

 this organism, as determined by the writer, were made at the Detroit 

 meeting of The American Association for the Advancement of Science 

 in August, 1897, and were pul)lished in tlie Proceedings of the Associ- 

 ation for that year (Vol. XLVI, 1897, Salem, June, 1898). 



Erwin V. Smith. 

 5 



