CORRUPTIO OPTIMI PESSIMA 145 



an exaggeration of it in old age. This pro- 

 bably occurs in wild nature as well as in 

 civilisation. Thus in Herrick's very careful 

 study of the European cuckoo, which leaves 

 its eggs to be hatched, and its offspring to be 

 nurtured by foster-parents, the suggestion is 

 made that there is in birds a harmonious 

 series or sequence of events linked to the 

 reproductive function, such as migration, 

 mating, nest-building, egg-laying in the nest, 

 incubation, care of the young in the nest, 

 care of the young out of the nest, and migra- 

 tion again. What may happen as a variation 

 is a disturbance of the harmonious sequence : 

 one chapter may be too long drawn out, as 

 when two nests are built, or another chapter 

 may be more or less suppressed, as when birds 

 desert their nest. 



Other sexual anomalies may be classified 

 as exaggerations, like some of the extra- 

 ordinary excitements occasionally incident 

 on falling in love, or like a hypersesthetic 

 sensitiveness to erotic stimulation. Others 

 are of the very opposite character an un- 

 natural frigidity and weakness of sexual 

 desire. Or it may be that the instinct is 

 awakened by abnormal excitations, whether 

 sensory (e. g. of touch or odour), or psychical 

 (e. g. by inflicting pain or by suffering pain). 

 Again there are the peculiar phenomena of 

 sexual inversion, or attraction to the same 

 sex instead of to the opposite sex, which used 

 to be regarded as an acquired viciousness or 

 as the banal consequence of some lesion, but 

 is now known to be frequently an innate per- 

 version of instinct. This cannot be inferred 

 K 



