RESUMEN
1. Newborn anthymic nude rats, innoculated with KB human tumor, normally develop a great level of tumoral taken. With the augmentation in volume of the tumoral mass, animals may enter in a cachetic state that leads them to death. 2. However, proportionally to the total of days of observation, the number of rats that enter in cachexia was significantly greater than in the group that did not develop growth of tumoral mass post-innoculum. 3. This fact may suggest that any factor produced by the organism, in an excessive amount, with the aim to hinder the development of the tumoral mass, ha d a parallel effect strondgly cachetizing. 4. Relevant is the fact that the production of this substance may be thymus-independent, since these animals are congenitally athymic