The Dutch animal psychologist Frederik J. J. Buytendijk (1887-1974) developed an anti-reductionist approach in his ethological research of the 1920s and 1930s distinct from behaviorism, explicitly including in his experimental practices the freedom of animals, variable observations, and the subjective experience of the investigator. Buytendijk thereby developed a scientific theory that methodologically relied on phenomenology, hermeneutics, and concepts of unity based on gestalt theory, but did not abandon quantitative data collection. On the contrary, in his Groningen institute Buytendijk based his work on the biological theories of Jakob von Uexküll and specifically investigated the thesis of an "animal-environment unit". Using this institutional framework and two experiments (1924 & 1931), this article determines to what extent Buytendijk was able to verify his statement that the animal was "born with and in its environment", which at the same time supported his scientific-philosophical concept. Accordingly, Buytendijk understood the environment as an organ of the animal, not only as a metaphor, but also as reality.