or the fecundating Dust of the Date Tree. 59 



particularly with that of magnesia, to prevent the alcohol 

 from separating it. Hence it follows that the phosphate of 

 masrnesia seems to have more affinity for the malic acid than 

 the phosphate of lime ; for there is no reason to doubt that 

 these salts are rendered soluble in water by their combina- 

 tion with the malic acid, as we have observed. We now see 

 therefore whv the alcohol takes up a portion of malic acid 

 from the mixture of the substances of which the extract of 

 pollen is composed ; also the reason why the residue depo- 

 sits phosphate of lime when we dissolve it in water; and, 

 lastly, why the phosphate of magnesia remains in solution 

 in the water, and reqtiires, in order to be separated from it, 

 the addition of ammonia, or of any other alkali. 



§ VIII, Examination of the Pollen washed and exposed to 

 the Air. 



After having found that water takes up malic acid from 

 the date tree, besides phosphates of lime and magnesia, and 

 a matter analogous to that furnished by animals, we pro- 

 ceeded to examine that part of the pollen which is com- 

 pletely insoluble in water. The pollen, well washed, was 

 placed to drip upon blotting paper : having been eight days 

 upon a shelf in the laboratory, in place of being dried, and 

 resuming its natural form of powder, its parts were softened, 

 glued together, and formed a kind of paste, in which a fer- 

 mentation took place which made it contract a smell ex- 

 tremely fetid, analogous to that of old cheese. This smell 

 had attracted the flies ; for we found plenty of larvs of these 

 insects which are nourished there. 



This matter thus altered, assumed when completely dried 

 a semitransparence, and a hardness which approached those 

 of strong glue. Before being entirely dried it was easily di- 

 luted in water, where it remained suspended for a long tiroe 

 and gave it the property of fiothing like soap. The water 

 in which we had thus diluted the mashed pollen was coao-u- 

 lated by the acids and the calcareous salts, which proves 

 that there was hjrmcd a kind nf soap during the fermenta- 

 tion which the pollen had undergone; the fixed alkalis libe- 

 rated 



