Proceeding from examples of biological theories the scientific-theoret
ical problem of uniformity of theories is discussed. Definitions of th
e ideas theory, scientifical theory and biological theory are given. B
iological theories have particularities in contrast to those of other
sciences. For its hierarchic order the field of validity and the struc
ture of biology is significant. The intertheoretical relations which a
re consisting between biological theories can be described as ''connec
ting-theories''.