EN
The endogenous rhythm of sporulation occurring in Penicillium claviforme differs from the non-circadian one. 1. The rhythm period is long being equal to 30 h in cultures grown in light. In darkness, sporulation is uniform. 2. The rhythm is maintained for 3-5 periods, and then it vanishes which is caused by desynchronization of the hyphae. 3. Synchronization is resumed after photocycles become employed (Piskorz-Bińczycka and Jerebzoff. 1989). 4. The rhythm may be induced in darkness by supplying a certain dose of light energy. 5. The rhythm is sensitive to some components in the nutrient medium: a) asparagine as an agent strongly controlling the periodicity is responsible for the maintenance of the rhythm for a 3-week period. Asparagine controls also the length of the rhythm period, however it does not induce rhythm in darkness; b) biotine is responsible for shortening the rhythm period; c) avidin effects the length of the rhythm period and the regularity of the newly formed rings; d) the amino-acids used did not permit complete elimination of an addition of yeast extract to the nutrient medium the concentration of which was reduced to 50%.