134 Methods in Plant Histology 



6. Differentiate in Weigert's ferricyanide solution. 



Borax 2.0 g. 



Ferricyanide of potassium 2 . 5 g. 



Water 200.0 c.c. 



7. Wash in water and proceed as usual. 



CANALICULI 



By using special methods, Bensley has obtained views of the 

 protoplasm of plants, quite different from those seen in ordinary 

 preparations. In the cell of a root-tip a series of small canals, or 

 vacuoles, appears, which is much more definite and extensive than 

 the usual diplay of vacuoles and which appears before any vacuoles 

 can be recognized in preparations made in the usual way (Fig. 24, B). 

 Being a zoologist, he has called these vacuoles canaliculi. 



Bensley's Fixing Agent. 



1. Formalin- (neutral) 10. c.c. 



2. Bichromate of potash 2.5 g. 



3. Corrosive sublimate 5. g. 



4. Water 90.0 c.c. 



Dissolve the bichromate of potash in the water, then add the 

 corrosive sublimate and finally add the formalin. The solution 2, 

 3, 4 will keep, but the formalin soon becomes acid. Add the formalin 

 to 2, 3, 4 only when needed for use. Obtain the neutral formalin 

 by distilling the ordinary commercial formalin. Proceed as follows: 



V 



1. Fix 24 hours. 



2. Wash in water, 24 hours. 



3. Iodize on the slide. 



4. Wash in water, 5 minutes. 



5. Copper acetate (neutral) saturated solution in water, 5 to 10 minutes. 



6. Wash in water, 1 minute. 



7. ^ per cent haematoxylin, 5 to 10 minutes. 



8. Wash in water, 1 minute. 



9. Potassium bichromate (neutral) 5 per cent in water till it blackens, 

 about 30 seconds or less. 



10. Weigert's ferricyanide solution until the preparation looks right. 



11. Wash in water and proceed as usual. 



