vi PREFACE 



to select the Frog for the purpose : after trying various 

 methods, I have found this plan to be the most satisfactory 

 in practice. 5. To give drawings and diagrams of difficult 

 dissections, and of details which the beginner cannot as a 

 rule make out satisfactorily for himself; but otherwise to 

 limit the number of illustrations so as not to tempt the 

 student to neglect observing the things themselves. 6. To 

 include a short account of methods and technique, limited 

 to the barest essential outlines, sufficient for a student 

 working by himself to make out the things described, but 

 not going into such details as would naturally be learnt in a 

 properly organised laboratory. 



In the meantime, my brother had in preparation a Biology 

 for Beginners, in which he intended to carry out the 

 plan, suggested in the preface to his Elementary Biology, 

 of giving a simple account, with practical directions, of one 

 of the higher animals and one of the higher plants, as 

 an introduction to the study of Biology. The animal he 

 selected was the Frog, and the manuscript of the greatei- 

 part of this section of the book was already finished and 

 the rest in rough draft. He had previously suggested that 

 some of this work might be utilised for our proposed Prac- 

 tical Zoology ; and I found that, with certain additions and 

 with modifications in the arrangement, the whole of it was 

 exactly the kind of introduction I had in view for the first 

 part of our book. Some of the illustrations that my brother 

 had intended to insert in the Biology for Beginners I have 

 found it advisable to omit, and even now the figures in the 

 introductory part are purposely nearly as numerous as those 

 in the rest of the book. But apart from these various minor 



