5 o SEX AND HEREDITY 



For once the Seer saw only a half truth. Had he 

 visualised with his accustomed clearness each germ, with 

 its deep-seated position, and its many protective coats ; 

 and realised how perfect are the conditions for nursing 

 the embryo in the maternal tissues, Literature might 

 have lost two epigrammatic lines, but Science would have 

 secured a truer word- picture. It is not at the outset, 

 but later in the individual life of Land Plants, that the 

 full weight of the physical struggle for existence comes. 

 In the period of embryology of new germs Nature appears 

 in her most engaging mood ; not " red in tooth and claw," 

 but as the nursing mother. That role is none the less 

 attractive that it has been forced upon her by the ruth- 

 less conditions of Life on Land. In aquatic Plants, such 

 as Ulothrix, Ectocarpus, or Fucus, the zygote has at once 

 to meet unprotected the contingencies of Life. Many 

 fail, but many succeed in passing that less drastic ordeal 

 of early existence in water. But the ordeal of life in the 

 air is more severe to the young in many ways. Hence 

 all Land Plants, as a condition of the bare existence of 

 their germs, have adopted the nursing habit. The ordeal 

 of the young organism is thus deferred. The embryo, 

 nourished and strengthened through the nursing period, 

 is better fitted to meet it than the naked zygote would 

 have been. This is the biological aspect of the facts 

 of internal embryology. The parallel in this between 

 the Higher Plants and the Higher Animals is singularly 

 close. While noting it, we should always bear in mind 

 that the results in the two Kingdoms have been independ- 

 ently achieved. They may be held as evidence of separate 

 reaction to the exacting conditions of terrestrial life. 

 But the incidence of these conditions has been the same 

 for both the Kingdoms of Living Beings. 



