Preservation of Teleostean Ova. 229 



of glacial acetic acid, they were also opaque when transferred 

 to any of the following fluids. 



Preservatives. 



Some dozen or so of picric mixtures were tried of which 

 the following are the principal : — 



(1) In equal parts of a sat. sol. picro-hydroch. ac. and 50- 

 per-cent. -alcohol ova of Trigla gurnardus shrank '1524 

 millim. ; the yolk was contracted and opaque ; the oil-globule 

 scarcely visible. In Pleuronectes platessa the shrinkage was 

 slightly less ^, being '1447 millim. 



(2) Sat. sol. picric acid 1 part, glycerine 1 part, 60-per- 

 cent, alcohol 2 parts. — Motella m/fs<e^/a shrank '1524 millim. ; 

 the oil-globule was fairly distinct. 



(3) Sat. sol. picric acid 2 parts, alcohol 1 part. — Results 

 very similar to method 1. Shrinkage fully '1524 millim.; 

 oil-globule poor and embryo indistinct, 



(4) Sat. sol. picric acid 2 parts, 50-per-cent. alcohol 4 parts, 

 2-per-cent. acetic acid 1 part. — Motella mustella and Trigla 

 gurnardus : oil-globule and embryo indistinct ; zona strongly 

 wrinkled. 



(5) Equal parts of sat. sol. picric acid, alcohol, and 2-per- 

 cent, acetic acid. — The following ova were preserved in this 

 fluid, of which theaverage shrinkage is given. The oil-globule, 

 where present, was remarkably clear. Embryos very distinct. 

 Ova previously prepared in other fluids, in which the oil- 

 globule was scarcely or not at all visible, speedily came to 

 view when allowed to remain in this fluid for five to twenty 

 minutes. 



Species. Average shrinkage. 



millim. 



Trigla gwnardus '1447 



Gadus morrhiia '1295 



ceglefinus "1295 



ntmutus •1143 



Motella mustella -990 



Brosjnius brosme •1371 



Hippoglossus limandoides "1524 



Rhombus Icevis •1371 



Arnoglossus Interna '1447 



Pleuronectes platessa '914 



Clupea sprattus '1143 



This was certainly the best of the picric solutions. 

 * The average is in all cases given. 



