Principles of western civilisation

52 WESTERN CIVILISATION CHAP,

heart of apparently the most inscrutable of all the problems which Darwin had left untouched. Weismann’s theory as to the period of the duration of life had gone to show that amongst the higher forms of life, so far from the duration of existence in the individual depending ultimately on any inherent molecular constitution of the cells of the body, it had throughout the various forms of life been lengthened or curtailed by Natural Selection just as the needs of the species had required. In the lowest or single-celled forms of life, however, there was nothing corresponding to the phenomenon of natural death at all. In these forms the cycle of existence was unending. Ata certain stage of growth each individual simply divided into two, each separate part of the parent continuing to live and grow until it again divided, and so on indefinitely. Hence arose the most daring inquiry to which biology had as yet advanced.

If in the lowest types of life the cycle of existence was normally unending: if in the higher forms the cycle of the life of the cells of which the body was composed was capable of being greatly lengthened out or of being rigidly curtailed just as the need

of the species required :—was the phenomenon of

the periodic death of the individual at the point at which it began to be encountered in naturenamely, amongst the multicellular forms of lifeto be considered as due to causes inherent from the beginning in the nature of the ce!ls themselves, any more than the length of the life-cycle in the higher forms of life was to be considered as due to such causes? In other words, had not this phenomenon also some relation to the law of