176 SUMMARY OF CURRENT RESEARCHES RELATING TO 



has not been able to detect the ultimate crystals in bar iron. My 

 sections of these show it splendidly, as will be seen when I exhibit 

 the microscopical photographs taken from the objects themselves. 

 What strikes me as so strange is that he has not appreciated the 

 total and complete difference between the intensely hard constituents 

 of blister steel and white iron, and soft iron of a malleable bar. 

 Possibly this may be in part due to the illuminative employed. The 

 direct illuminative contrived by me is so indispensable, that I feel 

 sure that no one can arrive at sound conclusions without it, and I feel 

 almost sure he did not use it." 



Microscopical Chemical Reactions.* — Herr A. Streng, from the 

 frequent application of chemical methods in the examination of rocks, 

 is enabled to improve and simplify the methods of microscopical 

 chemical research. He gives microscopical reagents for potassium, 

 sodium, lithium, calcium, strontium, barium, magnesium, aluminium, 

 and phosphoric anhydride. 



Hussak's Guide to the Determination of Rock-forming Minerals."]" 

 — The first part of this book deals with methods of research, describ- 

 ing Microscopes and apparatus, and giving directions for making pre- 

 parations. Optical methods and chemical methods of investigation 

 are detailed, as well as the mechanical separation of the minerals by 

 biniodide of potassium and mercury, biniodide of barium and mercury, 

 Klein's solution, acids, and the electro-magnet. 



The second and principal part (pp. 81-191) of the book consists 

 of well-arranged tables, in which the properties of the various minerals 

 are placed in columns (in some cases as many as seventeen), showing 

 at a glance the various points required to be known for their identifi- 

 cation. 



Whitman's ' Methods in Microscopic Anatomy and Embryology.'^ 

 — Dr. C. O. Whitman, of Boston, U.S.A., is well known to the readers 

 of this Journal as an able writer on all branches of microscopical 

 technique, and in this book he has brought together not only the 

 results of his own practical experience, but the principal methods in 

 use at the present time. The result is a well-arranged and very 

 useful work for the practical microscopist, and the more useful as it 

 has not been limited to histological requirements only, but includes 

 to a large extent embryological also. 



The book is divided into two principal parts, (1) general methods 

 and (2) special methods. The former includes methods of killing, 

 hardening, preserving, bleaching, macerating, decalcifying, desilici- 

 fying, staining, and imbedding, with a description of microtomes, and 

 chapters on fixatives for serial sections, mounting media, and the uses 

 of collodion. The special part is subdivided into embryological 

 methods, times and places of ovulation, nuclei, (karyokinetic figures, 

 &c.), preparation of nervous-tissue, histological methods, and recon- 



* Jahrb. f. Mineral., 1885, i. Mem. pp. 21^2. 



t Hussak, E., ' Anleitung zum Bestimmen der Gesteinbildenden Mineralien,' 

 iv. and 196 pp. and 103 figs. 8vo, Leipzig, 1885. 



% Whitman, C. O., Methods of Eesearch in Microscopical Anatomy and 

 Embryology,' ix. and 255 pp. and 37 figs., 8vo, Boston, 1885. 



