One hundred years ago, D’Arcy Thompson – a nineteenth century

polymath, working at the turn of the twentieth century – wrote a

beautiful monograph, “On Growth and Form”, in which he pondered

the geometry of living forms and how it emerges in the process of

Morphogenesis. Thompson was ahead of his time. Genetics and

Developmental Biology have since come a long way in elucidating

the general and particular aspects of Morphogenesis, uncovering the

key genes and molecules that underlie the process in different

animals and plants. Yet, Thompson’s agenda of understanding how

developmental processes actually specify the geometry of tissues,

limbs and organs is far from complete. A particular challenge is to

bridge the gap between microscopic scales, where molecular

mechanisms operate, and the macroscopic scales of animal “shape

and form”. This challenge offers much for a Theoretical Physicist to

think about. This talk will provide some examples, relating the study

of order in the arrangement of fly wing hairs to ferromagnetism and

uncovering an unexpected wealth of mechanical phenomena in the

study of cellular flows in a fly embryo.