PREFACE vii 



think, no longer a matter of practical concern to any- 

 body. When we examine a building we consider the 

 plan and its execution, but do not care to be told how 

 many bricks were dropped as the work went on. This 

 is the amiable view of official eulogists, and also of some 

 writers who, without being bound to praise, consider 

 nothing but economy of the reader's time. It may 

 appear to others that something besides positive achieve- 

 ment should be recorded. We want to know not merely 

 what was discovered, but how it was discovered. The 

 discoveries, even of great men, have often been vitiated 

 by serious mistakes, which have subsequently been cor- 

 rected by men of far inferior power. Whether in such 

 cases we give the whole credit to the man who first 

 indicated the process, or to the man who first arrived at 

 a true result, we do some injustice and at the same time 

 misinform our readers, who may fairly claim that in 

 important cases all the essential steps in the discovery 

 should be laid before them. We want to know how 

 some real discoverers began by trying false routes, how 

 others were impeded by time-honoured delusions, or by 

 overbold speculation. These things are part of the 

 story, and cannot be omitted without loss. 



The classics of natural history are not very much 

 studied in our own time. Few of them command high 

 prices, except those which treat of birds, or are richly 

 illustrated, or exemplify the history of printing and 

 engraving, and only public libraries take much pains to 

 enlarge their collections. Hence the works of such early 

 masters as Malpighi, Swammerdam, Eay, Leeuwenhoek 

 and E^aumur are still within the purchasing power 

 of ordinary students. I wish that every naturalist 

 might deem some acquaintance with them as part of 

 his equipment. 



