1884.] Microscopy and Histology. 651 
2) Transferred to boiling hot water for a short time. 
3) Placed in water and a little ammonia added ; this causes the 
contracted object to swell up to its original size and form. 
i 4) Neutralize the ammonia with a little acetic acid, and then 
6 Color with borax-carmine or ammonia-carmine. 
` (6) Wash and examine in dilute glycerine. 
The picro-sulphuric acid destroys the nutritive material; the 
ammonia dissolves any particles of fat that may be present; and 
thus the object becomes transparent so far as possible. 
A concentrated solution of corrosive sublimate may also be 
~ Used with success for killing Protozoa; but care must be taken to 
| wash thoroughly. 
Dr. Brass has obtained his best results without reagents or 
2. The nature of Chromatin—Dr. Brass has advanced an en- 
___ trely new theory in regard to the colorable portion of the nucleus. 
. Hitherto it has been very generally supposed that the chromatin 
: (Flemming) plays an important part in cell division, but Dr. 
Brass maintains that it represents simply surplus food-material. 
Opinion is supported by the fact that well-fed cells contain 
chromatin in abundance, while cells deprived of food for a con- 
le time appear to lose the chromatin. 
_ Prirzer's METHOD or COLORING AND HARDENING AT THE SAME 
_ TME’—To a saturated aqueous solution of picric acid add a 
_ Small quantity of an aqueous solution of nigrosin. This gives a 
deep olive-green mixture which kills very quickly and stains at 
the same time that it hardens. After a few hours’ immersion the 
ject may be transferred to water or alcohol for removing the 
a the oe which remains in a i eae 
: “end is very good for preparing small objects that have 
: to be killed, hardeed: Saied ae hater! the cover-glass. 
Picrerinc ReaGent Botrie2—The usual forms of filters of 
and cotton are not as convenient as one could wish, and it 
aheg a view to the production of a simple apparatus which 
deliver, perfectly filtered, any quantity of a staining-fluid, 
. ayid reagent from a single drop to a dishful, that I devised, 
3 bottle or eas ago, the bottle here described. A wide-mouth 
4 of convenient size is fitted with a cork through which three 
= apes ie ake the) a 
k are passed ; 
= the bottom of the bottle, while the other two tubes extend 
: On} ust below the cork 
beyond 
at d) is also fitted with a cork, through which passes a short 
piece of small tubing, which is slightly contracted at its distal end. 
ae Dtsch, Botan. Gessellsch., 1, No. 1, p. 44, 1883. 
ase ice the diameter of the first. The lower end of this larger 
YCEH 
