222 



would examine the milk of the papaw-tree just 

 as it flows from the stem or the fruit. 



The younger the fruit of the carica, the more 

 milk it yields ; it is found already in the gernien 

 scarcely fecundated. In proportion as the fruit 

 ripens, the milk, less abundant, becomes more 

 aqueous. Less of that animal matter, which is 

 coagulable by acids and by the absorption of 

 atmospheric oxygen, is found in it. As the whole 

 fruit is viscous it might be supposed, that, as 

 it grows larger, the coagulable matter is deposed 

 in the organs, and forms a part of the pulp, or 

 the fleshy substance. When nitric acid, diluted 

 with four parts of water, is added drop by drop 

 to the milk expressed from a very young fruit, a 

 very extraordinary phenomenon appears. At 

 the centre of each drop a gelatinous pellicle is 

 formed, divided by grayish streaks. These 

 streaks are simply the juice rendered more 

 aqueous, owing to the contact of the acid having 

 deprived it of the albumen. At the same time, 

 the centre of the pellicles becomes opaque, and 



* It is the same viscosity, which is remarked also in the 

 fresh milk of the palo de vaca. It is no doubt occasioned by 

 the caoutchouc, which is not yet separated, and which forms 

 one mass with the albumen and the caseum, as the butter and 

 the caseum in animal milk. The juice of a euphorbiaceous 

 plant, the sapium aucaparium, which also yields caoutchouc, 

 is so glutinous, that it is used to catch parrots. ( De Candolk, 

 loco tit., p. 263.) 



