[en] The interaction of nitrogen nuclei in nuclear emulsions has been studied experimentally and the number of incident nucleons which participate in the interaction has been determined. It is found that on average 75% of the nucleons emerging as free particles have interacted and produced pions. This number is close to expectation on the assumption that the incident nucleons in the nitrogen nucleus behave independently. Relevance to the important case of extensive air showers initiated by heavy nuclei is considered and it is shown that the commonly used superposition model is accurate enough for most applications. (orig.)