1. The relative weights of the gastrointestinal segments and of some other internal organs from light and heavy breed chicks from hatching to 21 days of age were compared.
2. The relative weight of the duodenum and jejunum was higher in the light breed than in the heavy one, the reverse relationship was found for the ileum and caecum.
3. The relative growth of the pancreas, heart, cerebrum and cerebellum was greater in the light breed.