76 



The Journal of Heredity 



actually does lay depends on the num- 

 her of nests which are available, that is, 

 on the amount of delegated parental 

 care on which she can rely. Again, 

 those fish which have no parental cares 

 produce an enormously greater nvimber 

 of progeny than do those fish v/hich 

 look after their young. These facts 

 ■seem to confirm my theoretical sug- 

 gestions. 



Thus far, we have been dealing with 

 theory and fact, and now I ask you to 

 follow me for a little in the path of 

 imagination. Shakespeare, generally a 

 sound guide both in fact and fancy, 

 tells us that the hedge-sparrow is a bird 

 whose nest is often invaded by the 

 •cuckoo.^ And I cannot but wish that 

 Shakespeare were here to tell us what 

 would happen if the cuckoo and the 

 hedge-sparrow became as good and as 

 wise as human beings. Would cuckoos 

 see the errors of their ways, and at 

 once begin building their own nests ? 

 That is asking too much — from cuc- 

 ■koos. Would they perceive that, if 

 they invaded too many nests, there 

 would be an insufficiency of hedge- 

 sparrows for their purposes in the 

 distant future? I doubt it, for a cuc- 

 "koo will always remain a cuckoo. Then 

 as to a wise and good hedge sparrow, 

 no doubt it would at once perceive that 

 the cuckoo's egg was a changeling for 

 'one of its own. But would this virtu- 



ous bird think it wrong to eject the 

 ugly intruder? And, if so, would she 

 limit the size of her family so as to be 

 able to give from the first undivided 

 attention to her uninvited foster child? 

 I do not know. I leave it to you to 

 answer these difficult questions. And, 

 in conclusion, I will only express the 

 hope that, when you hear the cuckoos 

 singing in the spring, the following 

 four questions may recur to your minds. 

 In the first place, have we not now 

 many human cuckoos living in our 

 midst; that is, persons of low morals 

 and poor intelligence, endowed with the 

 natural capacity for producing large 

 families, the main object of whose life 

 seems to be to throw the burden of 

 rearing their numerous offspring on to 

 the shoulders of others? Have we not 

 also among us noble-minded but mis- 

 taken human hedge-sparrows ; that is, 

 persons who, for the sake of easing the 

 strain on well developed but unscrupu- 

 lous human cuckoos, are ready to sac- 

 rifice all their own chances of becoming 

 parents of children of their own kind. 

 Again, in looking to the future of our 

 race, ought we not to consider quality 

 rather than quantity. Lastly, for mar- 

 ried couples designed by nature for the 

 task, is not one of their highest duties 

 on earth to take their part in peopling 

 the world with descendants hereditarily 

 endowed with noble qualities ? 



Shakespeare was in truth a little too hard on the cuckoo. 

 "The Hedge-Sparrow fed the cuckoo so long 

 That it had its head bit off by its young." 



— King Lear i, 4. 



Biology and Heredity 



dRUNnRLSS DER AlLGEMEINEN ZoOL- 



OGiE FUR Studierende, by Dr. 

 Alfred Kuehn, Professor of Zoo- 

 logy and Comparative Anatomy in 

 the University of Goettingen. Pp. 

 210. 170 illustrations. $1.10. Leip- 

 zig. George Thieme, 1922. 



This well-organized introduction to 

 ;gencral l)i')logy goes into some deta'l 



on Mendelian heredity, even to the 

 point of describing linkage and cross- 

 ing-over. The last section deals briefly 

 with species-building. After pointing 

 out that "pure lines" are artificial 

 products of breeding, the author in- 

 sists that the species is a "natural 

 genetic unit," because of the free 

 interbreeding of its members in a 

 state of nature. — P. P. 



