ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
453 
( = 20 /x x 100) representing the planes occupied by the sections. By 
means of the ocular micrometer the greatest diameter of each section is 
now measured, multiplied by 100, and half the resulting distance marked 
off on each side of the line representing the chief axis, and along that 
one of the parallel lines which corresponds to the section on which the 
measurement was made. For example ' The diameter of section 23 is 
0*588 mm. (found by multiplying the value of one division of the 
ocular micrometer — 17*2 /x — by the number of divisions covered by 
the diameter of the object, which, multiplied by 100, equals 58*8 mm., 
half of which is 29*4 mm.). This distance, then, is marked off on the 
twenty-third of the parallel lines and on both sides of the axial line,, 
thus giving the diameter of section 23 multiplied one hundred times. By 
repeating this process for each section and then joining the points thus 
obtained, there results a symmetrical outline at the desired scale. 
The outlines having thus been fixed, to plot the intestinal tract or 
any organ, it is only necessary to take measurements from one margin 
of each section to the nearest and farthest limits of the organ desired 
in the reconstruction, multiply the distance by 100, mark off the results 
on the corresponding parallel lines, and join the points as before. 
Though best suited for reproducing from transverse sections of 
bilaterally symmetrical objects, the method may be applied to any object 
of any shape, provided that a plane of definition at right angles to the 
plane of sectioning can be cut on some part of the object outside the 
organ which it is desired to reconstruct. 
Penetrating Power of Formalin Vapour.* — The results of the ex- 
periments made by Herr W. A. Iwanoff relative to the bactericidal 
action of formalin vapour are in conformity with those of other observers. 
The effect of the vapour is increased by raising the temperature — that 
is to say, it acts more effectively at the body heat than at room tempera- 
ture ; and not only on superficial parts, but also on deep-lying organs. 
Yet it is rather slow in its disinfectant action on deep-lying parts even 
when used at a high temperature ; for it took 3 hours to destroy fo wl- 
cholera bacilli in quite small pieces of deep-lying organs, while 4 hours 
were required for Metschnikoff’s vibrio, and 6 hours for anthrax, under 
similar conditions. When used at room temperature, it took from three 
to eight times as long. As might be expected, the action varies with 
the different organisms. A naked-eye inspection gives a pretty good 
notiou whether the disinfection is complete or not. If complete, the 
piece has become a whitish-grey colour, and is of a firmer consistence 
than before. 
Process for Soldering Aluminium in the Laboratory.^ — Mr. A. T. 
Stanton says that it is not easy to solder aluminium by using an alloy 
of definite composition without a flux, and has found that cadmium 
iodide is more satisfactory than silver chloride. If it be fused on an 
aluminium plate, decomposition of the salt occurs long before the melting- 
point of the aluminium is reached ; but the addition of zinc chloride 
obviates any great defects. Concentrated zinc chloride solution is mixed 
* Centralbl. Bakt. u. Par., l te Abt., xxii. (1897) pp. 50-8. 
f Nature, lvi. (1897) pp. 353-4. 
