94 PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



plants there is contained a variety of albumen which, when extracted 

 with warm salt solution and then allowed to cool, forms octahedral 

 crystals. 



Various forms of vegetable albuminous bodies have been described : — 



Vegetable Caseins.— The seeds of the leguminous plants and oleagi- 

 nous grains differ from the cereals, properly so called, in that they do 

 not contain gluten, soluble in alcohol, but, in addition to the albuminoids 

 coagulable by heat, various other albuminous bodies which are insoluble 

 in pure water but soluble in alkaline solutions, from which they may be 

 precipitated by acetic acid, the precipitate being soluble in excess. 

 According to Dumas and Cavours,this substance may even be coagulated 

 by rennet, and is therefore closely analogous to the casein of milk, to be 

 subsequently considered. Three different forms of vegetable casein-like 

 bodies have been described. Legumin, which forms the greater part of 

 the proteid constituents of the leguminous plants ; almonds and the 

 lupins contain a substance analogous to vegetable casein to which the 

 name of amandin, or conglutin, has been given ; while the part of gluten 

 which is insoluble in alcohol is of similar nature, and has been termed 

 gluten-casein. 



Legumin. — The watery extract of the seeds of the leguminous plants 

 often has an acid reaction, without doubt clue to the presence of phos- 

 phoric acid, which appears to be a necessary component of vegetable 

 casein. Legumin may be obtained by the agitation of powdered legu- 

 minous seeds with seven or eight times their weight of a one-tenth of 

 one per cent, solution of potassium hydrate. After about six hours the 

 fluid is decanted and allowed to stand from twelve to twenty-four hours 

 at a low temperature, and the residue which then forms is again washed 

 with water. The washings are then collected and precipitated with dilute 

 acetic acid, and the precipitate, washed again with dilute alcohol, is 

 finally precipitated by concentrated alcohol and ether. 



Freshl}- precipitated legumin is only very slightly soluble in cold 

 water. Legumin may, however, lie extracted from the powdered seeds 

 of the leguminous plants by cold water, its solubility in water being then 

 due to the phosphoric acid of the seeds. It is readily soluble in alkaline 

 solutions, from which it is precipitated by acids and solutions of metallic 

 salts. It is soluble in dilute hydrochloric and acetic acids. When boiled 

 with water it becomes coagulated and insoluble in alkaline solutions and 

 in acids. 13 y prolonged ebullition with sulphuric acid it undergoes 

 decomposition, with the formation of leucin and tyrosin and small quan- 

 tities of aspartic acid. Legumin is also present in oats. 



Amandin, or conglutin, is contained in sweet and bitter almonds, 

 and is separated from them in the same manner as legumin. It is dis- 

 tinguished from legumin liy a greater solubility in dilute acids, though 



