180 THE LAW OF BIRTHS AND DEATHS 



human beings. Therefore Doubleday's formula is quite 

 inadequate as an expression of the facts. 



The last chapter of Doubleday's book, however, is a 

 really remarkable one when read in the light of experi- 

 mental results obtained by scientists in recent years. A 

 series of experiments to test the action of various manures 

 on plants led Doubleday to the conclusion that " all 

 substances that contain portions, that is to say sensible 

 or considerable portions, of alkali in combination with 

 their other constituents may be expected to act, and will, 

 generally speaking, act as manures." He further con- 

 cluded as the result of his experiments that " the alkali 

 when it acts as a stimulant is caustic, or in part so." 

 Finally he came to the conclusion that " caustic and pure 

 alkali is the basis, or rather the stimulating principle of 

 manure. It is the principle which causes the seed to 

 expand, the plant to push, and the work of vegetable 

 growth to proceed." He further adds : " Pursuing the 

 inquiry upwards from the vegetable to the animal king- 

 dom, the next question is may not that which stimulates 

 the seed into life stimulate the egg into life ; and may 

 not one law here run throughout nature ? " In answer to 

 this inquiry there are certainly some facts which speak 

 strongly in the affirmative, and these are, that alkali, 

 that is to say soda, is found in the albumen of the eggs of 

 birds, and also, in company with ammonia, in the " liquor 

 seminalis " of animals, including man. Fourcroy, in his 

 analysis of the " liquor seminalis " of a healthy man, 

 detected both caustic soda and ammonia in quantity ; 

 and since his time the presence of active alkali in this 

 secretion has been placed beyond all doubt or question. 



So much then for the hypothesis. During recent years 

 a large variety of most significant experiments have been 

 carried out by Loeb, Delage and many other scientists 

 on artificial parthenogenesis and the cross-fertilisation of 



