1880.] 



MICROSCOPICAL JOURNAL. 



217 



but thei-e are a few which are found 

 here that are not described, and 

 several Parisian species have not 

 been observed in the United States. 

 Among our most common species 

 are Sp. quinina and Sp. rivularis, 

 neither of which are given in the 

 pamphlet; Sp. Jluviatilis closely 

 resembles our rhndaris. 



About Objectives. 



Not long ago a gentleman remark- 

 ed to us that he thought it was 

 about time for somebody to put an 

 end to the absurd and extravagant 

 writing in which a certain class of 

 niicroscopists have lately indulged, 

 concerning the value of very wide 

 angular apertures and unusual ma- 

 gnifications. The way he proposed 

 to end the matter was by putting 

 some very pointed questions to the 

 writers referred to, such as : " What 

 discoveries or new observations 

 have you made with your fine objec- 

 tives ? " Surely this is a very 

 practical and sensible suggestion, 

 for every microscopist knows very 

 well that the recent wide angled- 

 lenses have really contributed ahnost 

 nothing to our knowledge, in the 

 hands of American investigators, — 

 certainly nothing that is at all com- 

 mensurate with their cost, as com- 

 pared with other lenses of equal 

 excellence but of smaller angular 

 aperture. It is true that they are, 

 in certain respects, superior to the 

 latter, and in the hands of a few 

 investigators they have proved to 

 be invaluable aids ; but it is none 

 the less true that their superiority 

 is confined within such very narrow 

 limits, that only those who are en- 

 gaged in work that requires just those 

 qualities, will find such objectives 

 to be worth their additional cost. 

 It is to be understood that we refer 

 to persons who are engaged in what 

 is justly called scientific investiga- 



tion. At the same time, we would 

 clearly state it as our well-formed 

 opinion, that one of the greatest 

 improvements in the microscope 

 that has been made since Lister's 

 discovery of aplanatism, is the appli- 

 cation of the principles of homoge- 

 neous immersion. This application 

 lias led to great increase in the optical 

 capabilities of the microscope, and 

 no one who thinks at all can fail 

 to understand that the value of the 

 instrument, as a means of research^ 

 has increased thereby. However, 

 there are but few, comparatively, 

 who have need of the special advan- 

 tages which the greatly increased 

 angular apertures afford, and when 

 the choice of the student whose 

 means are limited, is between a ^-inch 

 at $34.00, and a better one at $70.00, 

 the cheaper lens will always be sold, 

 unless the other can be shown to 

 be much more useful. Even among 

 those who fully appreciate the 

 advantages of large angular aper- 

 tures (and the gentleman above re- 

 ferred to is one of these), it will 

 usually be found that the medium 

 apertures are considered to embody 

 the most useful qualities for routine 

 work, and the only way to effectually 

 combat this opinion, is for those who 

 favor the universal employment of 

 the large angular apertures to do 

 some original work and prove their 

 claims to be well founded. This 

 they can never do by mere argu-' 

 ments on paper, which are surely 

 not strengthened by the use of slang 

 phrases and vulgar expressions. 



Nectar. 



Mr. William Trelease is the 

 author of a very interesting pam- 

 phlet, published by the Department 

 of Agriculture, treating of nectar, 

 its occurrence and uses. It is illus- 

 trated by an excellent plate, showing 

 the stmcture of nectar glands and 



