106 Transactions of the Society. 



(f) Green when stained in Janus green intra vitam. 



(g) Dissolved by alcohol of 80 p.c. (Compare 3, c.) 



(h) Do not blacken in Flemming, with or without acetic. 

 (Compare 3, e.) 



Note paragraphs (a), (b), (d) and (e) for differences between Golgi 

 apparatus and mitochondria, and paragraphs (c) and (g) for close 

 similarity. Apart from these tests there are the facts of the shape 

 and position of the Golgi apparatus, and the number and shape of 

 mitochondria, which aid in discrimination between the two. (See 

 below.) 



3. Fat (Oil). 



(a) Black in Kopsch or Sjovall. 



(b) Not preserved by formalin followed by up-graded alcohols, 

 xylol, and paraffin-wax. This means the alcohol and xylol dissolve 

 it away. 



(c) Orange-red in an alcoholic (80 p.c.) solution of Sudan III, or 

 scarlet-red. 



(d) Left as empty vacuole after ordinary methods, such as 

 HgCl2 and acetic acid, or Bouin's fluid. 



Note. — Oil may, after osmic acid, be left as a vacuole with a 

 dark coagulum ; the same, however, may occur in a partly watery 

 and proteid droplet. 



(e) Preserved and blackened by a mixture of acetic acid 

 (5-10 p.c), chromic acid, and osmic acid (e.g. unmodified Flem- 

 ming's fluid). 



4. Yolk, Yolk Discs. 



(a) Yellowish, brown, to black in Kopsch or Sjovall, according 

 apparently to amount of free olein content, pure lecithin not 

 going black ; only greenish-yellow with OSO4. 



(b) Preserved in formalin followed by up-graded alcohols, 

 xylol, and wax. Generally shrunken after this. 



(c) Generally resists acetic acid (5-10 p.c.) in the presence of 

 osmic acid and chrome salts. 



(d) Earely left as a vacuole after ordinary methods (see 3, d). 



Note for differences paragraphs (b) and (d). Yolk may stain in 

 Benda's alizarin and crystal-violet, and possibly also in such a stain as 

 Altmann. Yolk often goes a greenish shade with OSO4, provided 

 the olein content is not too high. Yolk discs containing a good 

 fat content will give all the reactions in section 3, except (b) and (d). 

 In the fresh state some yolk is grey, but it often contains a pig- 

 ment (lipochrome). In molluscs yolk is grey in all the cases I 

 have met. 



