482 E. V. Cowdi-y, 



46 hours and stained with iron hematoxylin. By the use of this irok 

 hematoxylin method the mitochondria may be clearly seen after the 

 following- fixations: Beiida's fluid, Altmanii's fluid, acetic-osmic-bichro- 

 mate, Bensley's formalin-bichromate-sublimate and chrome-sublimate. 



The morphology and cytoplasmic arrangement of mitochondria are 

 the same after all these fixations. The preparations may be improved 

 by rinsing in water after staining in the iron alum, and then counter- 

 staining in a 1^0 aqueous solution of pyronin, or neutral red, or in 

 a saturated aqueous solution of safranin for from three to four 

 minutes. This brings out the Nissl substance very brilliantly. Com- 

 pare fig. 3 with Meves, 1908, plate XLII. 



6. The coji^jer- chrome -hematoxylin method. — The details of 

 Bensley's copper-chrome-hematoxylin method are as follows: 



I. Fixation. 



1. Fix spinal ganglia of the pigeon for 2, 4, 8 or 16 hrs. in either of the 

 following solutions. 



A. Acetic-osmic-bichromate mixture. 



2,5 °/o aq. soin, potassium bichromate 16 com. 

 2^/0 aq. soin, osmic acid 4 ccm. 

 Acetic acid two small drops. 



B. Altmann's osmic-bichromate mixture. 



b°jo aq. soin, potassium bichromate 10 ccm. 

 2''/o aq. soin, osmic. acid 10 ccm. 



2. Wash in aq. dist. 1 hr. 



3. Dehydrate in 50°/o, "i^O'/oj 95 "/0 and abs. ale, 24 hrs. each. 



4. Half abs. ale. and bergamot oil, 1 hrs. 



5. Pure bergamot oil, 3 hrs. 



6. Half bergamot oil and paraffin, 1 hr. 



7. 60° C paraffin, 2 to 8 hrs. Imbed. Cut sections A fi and fix to the slides 

 by the albumen water method, 



II. Staining. 



1. Pass down through toluol, abs. ale. 95°/o, 70 "/0 and 50"/(, ale. to aq. 

 dist. in staining jars. 



2. Sat. aq. soin, copper acetate, 5 min. 



8. Wash in several changes of aq. dist., 1 min. 



4. 0,5 "/u aq. soin, hematoxylin, 1 min. (If the copper acetate has not been 

 sufficiently washed out a black precipitate forms in the hematoxylin.) 

 The hematoxylin soin, should be well ripened. It may be obtained by 

 dilution down from a 10°/o alcoholic stock solution. 



5. Panse in aq. dist. 



6. S^/o aq. soin, neutral potassium Chromate, 1 min. (Sections should turn 

 a dark blue-black colour. If they are only a light blue shade, rinse in 

 aq. dist., place again in the copper acetate, and carry through as just 



