Page:Bergey's manual of determinative bacteriology.djvu/1009

 A KEY FOR THE DETERMINATION OF THE GENERIC POSITION OF ORGANISMS LISTED IN THE MANUAL

INTRODUCTION

The following key has been designed to enable the user to determine whether any isolated organism bears any resemblance to an organism described in the. Although the key terminates in most cases at a genus, it has been formulated on individual species descriptions. Every effort has been made to see that if the description of any species within the is applied to the key, the description will lead to the genus into which the species has been placed in the. Keys provided by the various contributors should be followed in deciding which species within the genus most closely agrees with the isolate. It is quite possible, owing to the limited description of many species, that the new isolate will be described more extensively and may fit into more than one species. It is unlikely, but not impossible, that it may fit into more than one genus.

No attempt has been made to fit the key to any system of classification. While it may undoubtedly act as a guide to the proper classification of an undescribed organism, it is designed solely for the purpose of identification of described species. The user must judge for himself whether an isolate is identical with a described species and, if not, determine its taxonomic position.

Characters were chosen solely for their suitability for purposes of differentiation and for the ease with which they could be determined. The sequence in which they have been employed was determined in part by common usage, in part by necessity through lack of other information and in part by design to encourage comparison of apparently closely related organisms and to enforce the use of some tests quite commonly ignored.

Where variation in any character has been well established, due allowance