64 Proceedings of the Boyal Physical Society. 



fore, there must liave been similar combinations of happy 

 circumstances fostering the occasional into the constant. 



III. Suggestion. — The theory which I have to suggest is, 

 that no special theory is required. What I mean will 

 become quite evident in the next few paragraphs. 



(1.) The general character of the cuckoo is very significant 

 Brehm describes it as a "discontented, ill-conditioned, passion- 

 ate, in short decidedly unamiable bird." " The note itself 

 and the manner in which it is emitted are typical of the 

 bird's habits and character. The same abruptness, insati- 

 ability, eagerness, the same rage, are noticeable in its whole 

 conduct." The cuckoos are notoriously unsocial, even in 

 migration individualistic. They jealously guard their ter- 

 ritorial " preserves," and verify, in many ways, the old myth 

 that they are sparrow-hawks in disguise. The parasitic 

 habit is consonant with their general character. 



(2.) The species consist predominantly of males. The 

 preponderance is probably about 5 : 1, though one observer 

 makes it five times greater. In so male a species it is not 

 surprising to find degenerate maternal instincts. 



(3.) Reproduction and nutrition, all authorities declare, 

 vary inversely. The love-impulses wane before those of 

 hunger. Now there is no doubt that even among greedy 

 birds the cuckoos hold a very high rank. They are remark- 

 ably insatiable, hungry, gluttonous. Even the anatomical 

 conditions, asserted by some to be important — the swollen, 

 low-set stomach, may have their influence in the cuckoo, 

 which has certain other peculiarities, though the same con- 

 ditions may be overcome in otlier birds which remain 

 perfectly natural. I miglit also suggest that the habit of 

 feeding so largely as cuckoos do on hairy caterpillars, whose 

 indigestible hairs form a feltwork in the stomach, may also 

 liave its irritant, gizzard-fretting, dyspeptic influence. But 

 I keep to the certain fact, and say that with so strong 

 imlritive impulses, it is little wonder the reproductive 

 emotions are degenerate. There is too much hunger and 

 gluttony for the higher development of love. 



(4.) The reproductive relations of the sexes are at a lower 

 level than polygamy, or rather polyandry; the males and 



