The development of form in living organisms continues to challenge biological research. The concept of biological information encoded in the genetic program that controls development forms a major part of the semiotic metaphor in biology. Development is here seen in analogy to an execution of a program, written in a formal language in the computer. Other versions of the semiotic or "nature-as-language" metaphor uses other formal or informal aspects of language to comprehend the specific structural relations in nature as explored by molecular and evolutionary biology. This intuitively appealing complex of related ideas, which has a long history in the philosophy of nature and biology, is critically reviewed. The general nature of metaphor in science is considered, and different levels of metaphorical transfer of signification is distinguished. It is argued, that the metaphors may be of considerable value, not only heuristically, but in order to comprehend the irreducible nature of living organisms. In arguing for a semiotic perspective on living nature, it makes a marked difference whether the departure is made from the tradition of F. de Saussure´s structural linguistics or from the tradition of general semiotics of C. S. Peirce. An agenda is made for a Peircean perspective on the semiotics of nature.