33 



may not the general conclusion be drawn, that the strength of vi- 

 tality of the impregnated ovum, or its power of resisting agencies 

 unfavourable to its life, gradually increases with age and the progress 

 of foetal development ? And as the Charr is one of the most delicate 

 of the family of fishes to which it belongs, may it not further be 

 inferred, with tolerable confidence, that the ova of the other and 

 more hardy species of the Salmonidee, were they similarly experi- 

 mented upon, would afford like results, confirmatory of those ob- 

 tained last year in some trials on the ova of the Salmon, and men- 

 tioned in my former letter to you ? 



The practical application of these results, and of the conclusions 

 deducible from them, is obvious, and need not at present be dwelt 

 upon. 



1 am, my dear Sir, 



Yours very truly, 



JOHN DAVY. 



Lesketh How, Ambleside, 

 January 10, 1856. 



II. " Note on a new Class of Alcohols." By M. AUG. CAHOURS 

 and A. W. HOFMANN, Ph.D., F.R.S. &c. Communicated 

 by Dr. HOFMANN. Received January 31, 1856. 



On submitting to dry distillation glycerine, either alone or toge- 

 ther with bisulphate of potassium or anhydrous phosphoric acid, 

 M. Redtenbacher obtained a remarkable product, to which he gave 

 the name of acroleine. Presenting all the characters of an aldehyde, 

 and approximating more particularly to vinic aldehyde by the general 

 aspect of its reactions, this substance changes under the influence of 

 oxidizing bodies, especially of oxide of silver, an acid being formed, 

 named by this philosopher acrylic acid, an acid which stands in the 

 same relation to acroleine as acetic acid does to aldehyde. 



The researches of MM. Will and Wertheim on the essential oils 

 of mustard and of garlic, tended to indicate a relation between these 

 substances on the one hand and acroleine and acrylic acid on the 

 other, a result which was established by the more recent investiga- 



