550 LIFE : OUTLINES OF GENERAL BIOLOGY 



have free-swimming pelagic larva?. Now in these two cases there are 

 no nerve ganglia at all, no more than strands and networks of 

 nerve-cells and their fibres ; and, in this absence of centralisation, it 

 follows that we must, in our descriptions of the behaviour, avoid as 

 far as possible any psychological implications. There is obviously 

 an objective parental care, but of a subjective side there is almost 

 as little hint as in a gooseberry-bush with its clustered fruits, or in 

 a tiger-lily with the bulbils hidden in the axils of its leaves. We do 

 not, of course, assert that the subjective side is absent in either case, 

 but keeping to the verifiable data, we do not at present know any- 

 thing about it. As there is an inborn predisposition or hereditarily 

 determined prearrangement in the dog-whelk to make a protective 



Fig. 84. 



A Holothurian {Cucumaria crocea), with numerous young ones (Y) attached 

 to the skin. After Report oj "Challenger" Expedition. TF, locomotor tube- 

 feet; T, tentacles. 



capsule for its eggs, or in the trapdoor-spider to sink a shaft which 

 secures their safety, or in a cuttlefish to fasten its egg-clusters among 

 marine vegetation, or in a mosquito to make buoyant egg-rafts 

 which cannot be sunk, so it is instinctive on the part of the brook- 

 leech to carry its young ones on its under surface until they are able 

 to fend for themselves. The fact is that near the commencement of 

 the inclined plane of parental carefulness we have mostly to do with 

 behaviour that is in the main the outcome of inborn or engrained 

 instinctive promptings— part of the hereditary make-up. 



At what level the parental care begins to be worthy of the name, 

 acquiring an emotional tone, who can tell? It seems very unlikely 

 that worker-bees, which nurse tlieir mother's grubs so loyally, have 

 more than a hint of awareness of what they arc doing, or more than 

 a hint of vicarious maternal emotion in their objectively unsurpass- 

 able solicitude. When a mother Sphex wasp provisions the cradles 



