This is of course merely a division of convenience since after its acceptance the doctrine of evolution has entered into all phases of biological progress. 

The portraits with which the text is illustrated embrace those of nearly all the founders of biology some of the rarer ones are unfamiliar even to biologists ave been discovered only after long search in the libraries of Europa and America orderly account of the rise of biology can hardly fail to be of service to the class of inquirers mentioned in the opening paragraph is oped that this sketch will also meet some of the needs of the increasing body of students who are doing practical work in biological laboratories is important tha such students in addition to the usual class room instruction should get perspective View of in which biological science has come into its present form. 

The chief purpose of the book will have been met if have succeede in indicating the sources of biological ideas and the main currents along which they have advanced and if have succeeded furthermore in making readers with those men of noble purpose whose work has created the epochs of biological history and in showing that there has been continuity of development in biological thought..