SPECIAL METHODS 
139 
1. Fix in formalin alcohol or in glycerin alcohol 4 or 5 days. 
2. Cut sections 8 to 12 /x thick. 
3. Ether, several hours. 
4. Absolute alcohol, 95 per cent and 50 per cent alcohol, 10 minutes each. 
5. Wash in water, 5 minutes. 
6. Iron alum, 4 per cent, 8 to 24 hours. 
7. Wash in water, 30 minutes. 
8. Stain in § per cent haematoxylin 24 hours. 
9. Wash in water. At this stage, examine carefully, because it may not 
be necessary to reduce the stain in iron-alum. If the connections are 
not too deeply stained, simply dehydrate, clear, and mount in balsam. 
After the first 5 stages, a strong stain in DelafiekTs haematoxylin, 
10 to 24 hours, followed by a very weak hydrochloric acid, has given 
Fig. 27 .—Diospiros Kaki: section of endosperm prepared as described for this species. X780 
good results. A sharp stain in crystal violet, differentiated with 
orange in clove oil, often fails, but sometimes succeeds; and, when 
successful, the connections stand out beautifully. 
The endosperm of Phytelephas (vegetable ivory), of dates and 
many other palms, and probably most hard endosperms, will show 
the connections by the methods just described; but in many cases 
it is necessary to resort to special methods in order to demonstrate 
the continuity. In these special methods a reagent is used which 
causes the membranes to swell before the stain is applied. It is only by 
such an exaggeration that the more delicate connections can be shown. 
