788 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the graphic reconstruction of organs or anatomical structures. Outline 

 sketches representing successive sections through the region under 

 investigation are made upon a series of these sheets and suitably coloured. 

 They are then built up in order, the correct centring of each diagram 

 being secured by bringing salient points into apposition. The sheets are 

 then stuck together by means of a hot iron applied to a corner at a safe 

 distance from the diagram. This method is peculiarly suitable for the 

 study of regions that are not unduly complex, and where the number of 

 sheets required is not so great as to interfere with transparency or 

 clearness. 



Morphological Demonstration of Methsemoglobin in Blood.* — G-. 

 Kronig has studied dried films of blood from cases of lnethaernoglobin- 

 aemia, with a view to finding out the details of the process of formation 

 of niethgemoglobin. After slow and careful heat fixation, films were 

 stained either by the methylen-blue-eosin or haematoxylin-eosin method. 

 From cases of poisoning with maretin and potassium chlorate, he obtained 

 films which showed distorted erythrocytes, haemoglobin and methaenio- 

 globin debris. Granules of pigment ingested by leucocytes were observed. 

 In films treated with an acid stain, small portions of protoplasm were 

 seen adherent to the pigment clumps. By this method, it is possible to 

 demonstrate methamioglobin even when a negative result is obtained 

 with the spectroscope. 



Shaw, E. H. — The Immediate Microscopic Diagnosis of Tumours at the time of 

 Operation. Lancet (1910) ii. p. 939. See also this Journal. 1907, p. 244. 



Metallography, etc. 



Metallography of Zinc.f — The impurities which may occur in com- 

 mercial zinc are lead, iron, cadmium, arsenic, antimony, tin, bismuth, 

 and copper. With the intention of applying the results to the examina- 

 tion of commercial zinc, P. T. Arnemann has studied the zinc-rich 

 binary alloys of zinc with the metals mentioned. The method adopted 

 was to construct the equilibrium diagram for the desired range from 

 cooling curves of the alloys prepared and from published data, and to 

 examine micro-sections. The softness of many of the alloys rendered 

 the polishing of sections very difficult ; surfaces for examination were 

 therefore obtained by casting on smooth surfaces. Glass, mica, quartz, 

 and steel were found to be unsatisfactory for this purpose, but good pre- 

 parations were obtained by allowing the molten alloy to solidify slowly in 

 a small wooden ring placed on the bottom of an inverted carbon crucible 

 heated by a gas burner. The lower face of the small ingot obtained did 

 not show the markings of the carbon surface in contact with which it had 

 solidified, but had the crystalline structure of the alloy. Alloys which 

 could not be prepared in this way were cut and polished. Among the 

 etching reagents used were dilute nitric acid, hydrochloric acid in alcohol, 

 and dilute copper-ammonium chloride solution. The thermal and micro- 



* SB. der k. Preuss. Akad. Wiss. (1910) pp. 539-47. 

 t MetaUurgie, vii. (1910) pp. 201-11 (65 figs.). 



