REPRODUCTION AND SEX 549 



offspring, my very own. For that is a somewhat subtle idea, reaching 

 beyond the vixen's wideawake determination that no intruder is to 

 be allowed to come between her and her cubs. How exactly she feels 

 no one can tell, but we are here simply concerned with defending 

 the common-sense thesis that the mammal-mother or the bird-mother 

 has real affection for her offspring and delight in their presence. 

 Why the emotions should gradually wane away as the offspring 

 cease to be young is a problem by itself; but allowance must be 

 made for the limitedness of the animal mind, which passes readily 

 from one preoccupation to another. New interests and problems, or 

 older ones revived, crowd out the parental affection ; moreover, the 

 youngsters cease to make their childish appeals and may eventually 

 become intolerable rivals. And while we are insisting that the 

 mental aspect — the stream of feeling — is a vera causa that counts 

 for much, we are not for a moment denying that its activity may 

 wane away because of profound changes in the body to which the 

 mind is thirled. Nemo psychologus, nisi physiologus; and vice versa. 

 Emotions are real, and so are the endocrine glands; perhaps they 

 are the two sides of one shield. 



Now let us pass from the highest animals to near the foot of the 

 inclined plane on which the grades of parental care may be arranged. 

 There we find many cases where the eggs develop in contact with 

 the parent, being attached to the skin, as in the brook-leech and 

 the Surinam Toad, to some of the limbs, as in the crayfish and the 

 sea-spider, or in some sort of pocket, as in some quaint fishes, or in 

 some other way. This carrying of the eggs is an advantageous 

 adaptation, with its counterpart in plants, which secures their 

 safety; and it points the way to those cases where the young ones 

 are similarly carried about for a prolonged period. Being accus- 

 tomed to carrying the eggs may make it easier for some simple 

 animals to acquiesce in carrying the young ; and the automatisation 

 of this is illustrated by those male crabs that have been castrated 

 by a Cirriped parasite (Sacculina, etc.), and behave, in their strangely 

 feminised state, to the protruding parasite as if they were females 

 and it a bunch of eggs. In the lower reaches of parental carefulness 

 the physiological aspect is dominant. Moreover, it is not difficult to 

 find reasons why the newly hatched young, on their part, should 

 sometimes adhere to the congenial safe surface afforded by their 

 mother's skin. Their protoplasm in the course of development has 

 become accustomed to it. 



In a few female sea-cucumbers or Holothurians the young ones 

 are carried about embedded in the skin ; in one of our British star- 

 fishes the young ones, which are in this case like miniatures of the 

 parent, may be seen clambering about on the outside of their 

 mother's body and keeping firm hold as she moves — a very different 

 kind of early development from that seen in most starfishes, which 



