The architecture of the C2 3A. (Chambres de Culture Automatique en Atmosphères Artificielles) system for the controlled study of plant physiology is described:1) Modular plant growth chambers and associated instruments (I.R. CO2 analyser, Mass spectrometer and Chemical analyser).2) Network of frontal processors controlling this apparatus3) Central computer for the periodic control and the multiplex work of processors. It also concentrates the data, obtained from processors, and stores them in long term data base.4) Network of terminal computers able to ask the data base for data processing and modeling.Examples of present results are given : growth curve analysis, study of CO2 and O2 gas exchanges of shoots and roots and daily evolution of algal photosynthesis and of the pools of dissolved CO2 in sea water.This system is extremely useful to continue progress in agricultural research. Another application is in Controlled Ecological life Support Systems (CELSS) for space habitats.