(iy) PREFACE. 



Summaries of Progress would be sufficient alone, without 

 any paragraphs recording individual discoveries. It would, 

 of course, be impossible to satisfy such discrepant opinions, 

 and in this dilemma the only resource left to the editor 

 lias been to follow a mean which he hopes will be re- 

 garded by most as a tolerably happy one. It must be re- 

 membered that far more than ten times the space con- 

 tained in the present volume would be necessary to give 

 even an approximately complete abstract of the progress 

 of science in each of the departments embraced within 

 the scope of this work: much more than that amount 

 will in fact be employed in the annual reports that are 

 hereafter to be made and published on the progress of the 

 several departments of science for the past year. These 

 reports, for 1875, however unlike the present volume 

 will not appear till at least one, and, in some cases, two or 

 three or even four years have elapsed. These too are, to 

 a certain extent, addressed rather to experts and special 

 students in the various branches of science than to the 

 general reader, for whom the "Annual Record" is more 

 especially designed. In them the several branches em- 

 braced herein are respectively reported upon, in volumes 

 varying from little less than five hundred pages to nearly 

 two thousand each year. Each special department of sci- 

 ence has now its own organ for the record of discoveries 

 within its domain. All these are extremely useful to the 

 investigator, and enable him to economize precious time, 

 that would otherwise be spent in frequent reference to 

 numerous volumes, some of which are almost or quite in- 

 accessible to all save a favored few. Several, also, are 

 very elaborate, and the special subdivisions within a single 

 branch are reported upon by experts in the respective sub- 

 divisions. Excellent examples of such reports are found in 

 the JaJiresberichte and Jahrbucher, published in Germany, 

 on the mathematical, physical, and chemical sciences. 

 Some branches have even two or more annual works de- 

 voted to the record of progress in their several spheres ; 

 such are especially Zoology, on which one report is pub- 

 lished in Germany and another in England ; Botany, 



