Constant Climatic Conditions Research Articles

Studies on Growth and Development of Some Herbaceous Phanerogams under Controlled Conditions

l. The basic temperatures for growth of Ageratum houstonianum 'Capri', Calendula officinalis 'Dania', Scabiosa atropurpurea 'Imperial' and Tagetes patula var. nana 'Naughty Marietta' were estimated to be 8, 2, 4, and 60C respectively. The plants were raised under constant climatic conditions at temperatures of 3, 6, 9, 10, 12, 15, 18, and 21C. 2. The plants tended to be tallest at intermediate temperatures (15 and 18'C). At 210C the elongation growth was partially inhibited, especially in Scabiosa. At the highest temperatures Tagetes and Calendula reached first a maximum total length and then decreased somewhat again possibly because of decrease in turgor pressure after flowering. Internodal length was found to be positively correlated with temperature. 3. For Ageratum, Calendula and Tagetes the

The J Substance of Cattle

Summary Sera and saliva of about 67% of 300 rabbits contained a substance which was capable of inhibiting the reaction between cattle anti-J serum and J-positive cells. The presence of this J-like substance in rabbit serum and presumably in saliva is controlled by an autosomal dominant gene. A J-like substance was found also in a nondialyzable fraction of rabbit urine. Rabbits lacking the J-like substance when injected with saliva from cattle containing J produced specific immune anti-J. Naturally occurring antibodies of rabbits did not show seasonal variation, but this could possibly be explained by the constant climatic conditions under which the rabbits were kept.

Évolution quantitative de l’acide β indol-acétique chez Hyosciamus niger, en rapport avec la sexualisation et la floraison

Studies on the metabolism of β indolyl-acetic acid, occuring naturally in the leaves during the growth and development of Hyoscyamus niger, grown in 16 and 8 hours days in the constant climatic conditions of the Phytotron at Liège, have shown that : (1) The evolution of the IAA content, during the first days of growth, is the same whether the plants are in long days where they will flower, or in short days where they will not. However it is during this period that the plants, put in long days, begin to pass from the vegative to the sexual state. This has been shown by the method of transfer. The evolution of the content of free and bound IAA gives no distinction between the sexuated and non-sexuated plants. (2) After the period of the sexualisation of the plants in long days, the metabolism of IAA shows fluctuations which coincide with the growth of the flowering stalk, the emergence of the flowers and the formation of the fruits, as has already been shown by R. Bronchart with Sinapis alba. With the plants in short days the evolution of IAA does not undergo any fluctuations, but increases continuously in the leaves for many weeks. This divergence in auxin metabolism appears then as a consequence of the sexualisation of the plants in 16 hours days.