— 75 — 
employed the classical, diluted solution of potassium-hichromate 
(0.03 — o.i 7o)- Maceration in this fluid for several days, and stain- 
ing in ammonia- car mine diKited with or dissolved in the macerating 
fluid gives very good preparations. A shorter staining with diluted 
hæmatoxylin may also be recommended. Upon the whole, macera- 
tion in potassium-bichromate is a method which cannot possibly be 
omitted, if the most delicate structure is intended to be disco- 
vered and explored with good results; it is certainly one of the 
oldest methods but also one of the best. 
By the use of ammonium-bichromate, in very diluted solution 
(0.03 — 0.1 7o)' results are, I think, obtained very similar to those 
obtained by potassium-bichromate. The difference is, at all events, 
not so great as to make it necessary to dwell upon it here. 
A maceration-fluid which is, I think, for many purposes very 
good, is that originally suggested by Landois, and subsequently 
recommended and described by GlERKE. ^) It consist of a mixture 
of: chromate of ammonium (concentrated solution i part), phosphate 
of potassium (conc. sol. i part), sulphate of sodium (conc. sol. i part), 
Aqiia clest. (20 parts). 
The sections or small pieces are macerated for one or several 
days, then stained with ammonia- car mine, picro-carmine or diluted 
hæmatoxylin. The dilution of ammonia-carmine with this macerating 
fluid, as recommended by GlERKE, is, according to my experience, 
not possible, as the carmine is precipitated. The isolation by this 
method is a very perfect one. The more delicate structures are, 
however, slightly visible, as they become too transparent. 
The most important thing in researches upon the histology of 
the nervous elements is, beyond comparison, to get good sections from 
well fixed and stained preparations. This is, no doubt, the surest 
and most decisive method. A very careful preparation is, here, 
however, of the greatest importance. 
A splendid fixing, and at the same time hardening, agent is the 
chromo-aceto-osmic acicl (Flemming's strongest formula), which for 
our purpose affords really excellent results. I have employed both 
of Flemmings formulæ and think the strongest one the best. It is: 
Chromic acid . . i % ^5 parts 
Osmic acid . . . 2 7o 4 
Acetic acid ... i » or less. 3) 
'') As recommended by Gierke (1885, x\rch. mikr. Anat. Bd. XXV p. 447)- 
-) 1. c. 1885 p. 446. 
•■') Flemming: Zeitschrift f. wiss. Microscopie Bd. I. 1884 p. 349. 
