StronG, Technique of Weigert's Method. 297 
ing, in the above-mentioned neutral haematoxylin for 4 to 12 
hrs., the shorter period being found sufficient. As in all WeEI- 
GERT methods, old or used solutions of haematoxylin must be 
avoided. The sections are then decolorized in 1% or 2% iron 
alum, the decolorization proceeding slowly and evenly. With 
any degree of care, over-decolorization is easily avoided. After 
decolorization, the sections, now being a faint pinkish hue, are 
washed, dehydrated, cleared and mounted. 
With this method the peripheral nerves in Squalus were well 
fixed and stained deep blue. The color was completely removed 
from all other tissues except the denticles and sometimes por- 
tions of cartilage. The central nervous system was not as well 
fixed nor stained, but presented a fairly good WEIGERT picture. 
The decalcifying power, simplicity and certainty of this 
method recommend it for such work. The tendency of the 
iron alum-formalin to overharden and make the tissue difficult 
to section is perhaps the principal defect. With the loose tis- 
sues of the young shark this objection was not realized as it 
would be with other objects. 
This method has been reported by Herrick (State Hos- 
pitals Bulletin of N. Y. State, Oct., 1897, p. 27 and Journal of 
Comparative Neurology, Vol. VIII, Nos. 1-2, July, 1898.). 
Conclusions. Though many of the combinations in the 
above lists have not been sufficiently tested, yet from these data 
and from other observations of the writer, the following con- 
clusions which may in cases be of practical value may be 
drawn. 
(2) Fixation and hardening in formalin alone appears to be 
preferable in some respects to fixation and hardening in potas- 
sium bichromate + formalin followed by further hardening in 
potassium bichromate. The latter method is capable of yielding 
fine preparations, but at times it appears difficult to secure them 
by the ordinary procedures. Furthermore. in such material 
the medullary sheaths when stained often exhibit a vacuolated 
appearance, due apparently toa staining of the neurokeratin 
network, which detracts from the brilliancy of the preparations. 
