RESUMO
A correlation between the functional activity of the synthesis apparatus of blood lymphocytes in different animals and the variations in the neutron count rate near the Earth surface has been studied. From 1999 to 2002 for rats and from 2002 to 2003 for ground squirrels, a reliable positive correlation between the synthetic activity of animal blood lymphocytes and the neutron count rate was found. The correlation was observed for both the neutron flux directed towards the Earth and the total neutron flux (the neutron field of the Earth). There was no a correlation for the neutron flux directed away from the Earth in this period. In 2005-2006, which is characterized by a minor variations in the neutron count rate, no correlation was observed. Thus, the biotropic effect of thermal neutrons makes its self-evident as changes in the functional activity of blood lymphocytes in periods of significant variations of neutron fluxes.