904 SUMMARY OF CURRENT RESEARCHES RELATING TO 



freed, object removed, and cell rccoatcd, or the cover simply cleaned 

 and replaced as before in a minute or two, and thus objects too hastily 

 mounted may bo remounted or recovered with the least loss of time, 

 which caimot be done so well or so quickly where covers have been 

 cemented down with any of the cements ordinarily used." 



Mr. R. Hitchcock has found, however, that since ho has been in 

 Washington a great change has taken place in his slides, and that the 

 covers are now quite generally coated with the deposit complained of. 

 It should bo remembered that in this case the mounts remained in a 

 perfect condition certainly four or five years, and then the change 

 took place. 



The Microscope in Mineralogy.* — Prof. J. W. Judd writes as 

 follows : — 



The recognition of certain characters in the rock-forming minerals 

 as being original and essential, and the distinction of such from other 

 characters which are secondary and accidental, is of the highest 

 importance to the petrographer and geologist, and not less so to the 

 mineralogist. Rightly studied, these minerals are capable of furnish- 

 ing the geologist with evidence not only concerning the mode of 

 origin of the rocks of which they form a part, but also of the changes 

 which they have undergone since their first formation. The study of 

 the minerals included in the crystalline rocks is not less important 

 than that of fossils in the sedimentary rocks. And to the minera- 

 logist the study of the secondary characters of minerals, and of the 

 causes which have produced them, is equally necessary. Researches 

 of this kind, indeed, can scarcely fail in the end to reduce many so- 

 called mineral species to the rank of accidental, though still highly 

 interesting varieties. 



But of still greater importance is the recognition of the fact that 

 the investigation by the aid of the Microscope of the processes by 

 which minerals have acquired their several characters, and the conse- 

 quent tracing of the evolution of mineral species and varieties, is 

 calculated to raise mineralogy from its present rank as a merely 

 classificatory science, to infuse it with new life, to open out to it new 

 realms of research, and to invest it with a higher importance than is 

 at present accorded to it in the family of sciences. 



Amphipleura pellucida in various mounting media. [Supra, p. 902.] 



Nature, XXIV. (18S6) p. 355 (Proceedings of 



R. Soc. N. S. Wales, June 2nd, 1886.) 



Bachmann, E. — Mikrochemische Reactionen auf Flechtenstoffe als Hulfsmittel 



zum Bestimmen von Flechten. (Micro-cheinical reactions of Lichen-substance 



as an aid to the determination of the Lichens ) [Post.'] 



Zeitschr.f. Wiss. Mihr., III. (1886) pp. 216-9. 

 [Beck, J. D.] — New Methods and Mailing-boxes. 



["This method of double-staining vegetable sections consists in employing 

 such means whereby it is possible after staining to dehydrate the sections 

 in absolute alcohol without having the colour in the least removed by the 

 alcohol. Mr. Beck ' does not feel able to give the process to the public, 



Quart. Journ. Geol. Soc, xli. (1885) p. 411. 



