INTEODUCTOEY. XIX 



Dr. Loew, throughout his entire connection with the Expedition, has 

 each year contributed largely to the botanical collection. I am also 

 greatly in debt to him for much of the material embodied in Chapters I, II, 

 and III of the text. 



I have avoided any change, as far as I could, in the manuscript of 

 the gentlemen associated with me in preparing this report, thinking that 

 a mere uniform mode of expression was of less importance than that each 

 author should state his facts in his own way, and thus avoid the introduc- 

 tion of any errors of my own. 



The preliminary portions, i. e., Chapters I, II, and III, J have pur- 

 posely made popular and avoided all possible technicalities, for obvious 

 reasons. These same parts have also been made much shorter than was 

 originally intended, because the remainder of the volume so much exceeded 

 the limit at first assigned ; and, further, because much of the material found 

 its way into Chapter IV. 



The plates drawn by Messrs. Sprague and Seaman, and engraved by 

 Julius Bien, need no comment from me. The name of each artist is con- 

 nected with his work. 



There remains now but the pleasant duty of adverting to the generous 



aid always rendered by you, and by the gentlemen associated with you, 



both in field and herbarium work, and also by the officers of the various 



posts I have from time to time visited in performance of my field duties. 



Without the encouragement received from you and from them, no labor of 



mine could have collected the material for this report. 



Very respectfully, 



J. T. ROTHROCK. 

 First Lieut. Geo. M. Wheelek, 



Corps of Engineers, TJ. 8. Army, in Charge. 



Note, December 31, 1878. — Since the manuscript for this Report was 

 completed, the first volume of the Flora of California, by Messrs. Brewer 

 and Watson, has been published ; and we have reason to hope for the 

 speedy appearance of the second. This, of course, reduces my labor, so far 

 as the collection of 1875 is concerned, to merely enumerating the plants 

 and adding a few fieldnotes. Anything more would have been not only 



