32 American Quarterly Microscopical Journal . 



On Fodura, after what I have already said, I need 

 scarcely remark that the same difference was apparent. 

 Indeed, as the same oil is not suitable both for extreme and 

 for central illumination, and I had but that which the owner 

 of the objective sent with it, it is not, perhaps, fair to M. Zeiss 

 to dwell too strongly upon this test. Now, in all I have said, 

 I beg not to be understood as depreciating the Zeiss objective. 

 It is, by far, the best foreign objective I have ever handled. 

 There was a satisfaction in being relieved from any responsi- 

 bility in adjusting. For my own part, I felt so much satisfac- 

 tion in this, that I hope the Spencers may be induced to make 

 similar objectives. Finally, it must be remembered, even 

 granting for a moment that my excellent friend in Germany 

 did succeed in resolving test objects much better with the 

 "Zeiss" than with the "Spencer," that the latter was also a 

 very good objective as a dry, and there are hundreds of cases 

 where an oil, which dissolves balsam, and asphalt, etc., cannot 

 well be used ; or possibly he may have employed water as the 

 immersion fluid, which is only proper for direct (axial) illumina- 

 tion, instead of glycerin, which is necessary for very oblique 

 illumination 



THE MICROSCOPICAL EXAMINATION OF FIBERS. 



BY W. H. SEAMAN. 



Numerous isolated observations on this subject maybe found 

 in works on microscopy, but few attempts have been made to 

 unite these in a connected system.* Many of the statements 

 floating in popular journals are erroneous, and as the determin- 

 ation of the nature of fibres is one of the questions often pre- 

 sented to the microscopist, we offer the result of our experience. 



A fiber is any flexible filament used in making cordage or 

 woven or felted fabrics. 



They may be compared with each other as regards their — 



1. Origin, animal or vegetable. 



2. Form of section, diameter and length. 



3. In animal fibers, color, surface and general shape. 



4. In vegetable fibers, diameter and length of ultimate cells. 



* The best treatise yet published, is " Vetillart sur les fibres vegetales employes dans I'lndustrie." 

 See also a special report by Hunt & Schaffer, Bulletin Nat. Ass. Wool Growers, 1873. 



