934 JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, Vol. XVII. 



quoted above of two such eminent naturalists as Prof. Ray Lankester and 

 De Vries, however, can hardly be held to justify such a conclusion. 



8. Before proceeding further it may at once be asked whether the accurate 

 defining of the word species is, or is not, of great practical importance. 

 That it is of the greatest importance can, perhaps, be best shown by assuming 

 that we abolish the term and the conception of species and adopt the only 

 other obvious basis for classification, viz., the degree of resemblance or differ- 

 ence between individual organisms ; in other words, let us adopt the suggestion 

 of Professor Ray Lankester to " describe, name, draw, and catalogue forms." 

 Then so long as organisms retain their power of reproduction, since no 

 individual organism ever exactly resembles another, there would, in the first 

 place, be no limit to the number of names which would be required ; secondly, 

 only an exceedingly minute fraction of the total number of forms existing 

 on the earth at any given period could ever be possibly described ; 

 while, thirdly, these descriptions would be useless for the purpose of 

 identifying living forms after the death of the individuals to which 

 they particularly refer, i.e., they would be useless to our successors, 

 and practically useless to ourselves. The undoubted fact that, within 

 certain limits, all organisms breed true, appears thus to afford the only basis 

 for. a natural history classification which shall be of practical value. By 

 discovering within what limits each different kind of organism breeds true, 

 i. e. the characters which are always transmitted to its immediate offspring, we 

 can alone hope to obtain and be able to define a unit, vis., the species, which 

 so far as we can see is permanent, and which, in consequence, can be recog- 

 nized and studied by our successors. Also, by only giving a separate name 

 to each such unit, instead of to each distinct form, the number of names which 

 will be required is enormously reduced. 



Moreover, until this unit, the species, has been accurately defined, our 

 classifications cannot be considered to be established on a sound basis, for, 

 until this is done, it is obviously impossible to decide whether, or not, we are 

 unnecessarily increasing the number of names and wasting labour in describing 

 unstable, ephemeral forms. 



9. Granted it is advisable to define a species, the question remains, is it 

 possible? Seeing no reason why this should be impossible, I have drawn up 

 the following tentative definitions and explanatory notes, which, while em- 

 bodying what are believed to have been the central ideas of the Linnean 

 conception, are thought to be also fairly in accordance with modern know- 

 ledge. It is hoped that their criticism will indicate what principles are capable 

 of general acceptance. For the sake of brevity I have taken my illustrations 

 in the explanatory notes from botany, but it is believed that the main 

 principles embodied in the definitions are also applicable to zoology. 



10. Before giving the definitions, a point which, although of the greatest 

 importance, is frequently overlooked, must be noted, viz., that a distinction must 

 be made between organisms which live and are developed in a natural state, 



