PREFACE TO THE REVISED EDITION. 



The first edition of the Course of Practical Instruction in 

 Elementary Biology appeared twelve years ago, and the 

 motives which led to its publication are fully explained 

 in the original preface, which is subjoined. The present 

 edition has been carefully revised and, where necessary, 

 enlarged by my colleagues Mr Howes and Dr Scott, assistant 

 Professors in Zoology and Botany in the Normal School of 

 Science and Royal School of Mines, and such additions 

 and improvements are entirely their work. But besides 

 these changes, the reader who compares the two editions 

 will observe that the order in which the subjects are pre- 

 sented is completely changed. In the first edition the 

 lowest forms of life were first dealt with; the series of 

 plants followed in ascending order ; and then the series of 

 animals, from the Bell animalcule upwards to the Frog. 



No doubt there is much to be said for the principle of 

 this arrangement, which leads the student from the study 

 of simple to that of complex phenomena ; but the experience 

 of the Lecture-room and the Laboratory taught me that 



