xiv DKs.Nims OF THE I'M TED RTATE8. 



case of tin' Desmids, is of little importance; nevertheless, when 

 practicable, always examine the material when fresh. When 1 tn < 1 

 mi paper for the herbarium, the specimens can -till, after being 

 moistened with water, he microscopically examined, but nol with 

 the best results, since the drying i- apt t< collapse, or < >t 1 1 -rw i-< 

 distort the cell-. 



The collector will not know the value of hi- find, until it has 

 been brought drop by drop under tin [ens of hi- microscope, ami 

 out of the entire i n;i -- he may discover nothing t<> reward his 

 labors; this however should nol discourage him, as "tie or two 

 failures are to be expected prior to meeting with an adequate reward. 

 His interest in the study will be greatly enhanced it he keeps :i 

 record of it in sketches of what the microscope reveals t<> him. 

 These sketches should of course, 1 very exact, and in order thai 

 they may he -<>, it i- necessary that the microscope should be pro- 

 vided with an eye-piece micrometer with which \>> measure the 

 length and breadth <(' tin figure to he sketched ; ;i hall' inch per 

 j-jAj-g (.001") or _'" fi is the most convenient, though \ <>r \ of 

 an inch may be ;i preferable scale for the larger forms. It is so 

 difficult to separate specimens from their accompanying foreign 

 matter, that it is seldom amateurs can mount tie m satisfactorily on 

 slides, and therefore this method of preserving sj>ecimens is not 

 open to recommendation. 



Although in the microscopic study of the fresh-water A Iga much 

 has been dune within the |>;i-t few years, much more remains t< be 

 accomplished. The field instead of growing -mailer seems t widen 

 out with every fresh discovery ; localities thought to have been 

 exhausted of additional possibilities, have in subsequent seasons, 

 yielded ample return- to the patient explorer; and if the old 

 territory is not sufficiently attractive, there are vast regions into 

 which no student has yet penetrated, where, doubtless, the barv< st 

 awaiting the reaper dwarf- all that ha- l>een heretofore garnered. 



