Volume 34, Issue 2
August 1951, pages 63-113
pp 63-72 August 1951
pp 73-80 August 1951
pp 81-91 August 1951
The adsorption ofB. subtilis andB. coli by two well-known adsorbents—kaolin and charcoal—has been quantitatively investigated at various concentrations of the bacterial suspensions. On plotting the data the total number of organisms adsorbed by unit mass of the adsorbent against the equilibrium concentration (number of organisms per c.mm. after adsorption)—typical S-shaped curves were obtained. This shape is a characteristic feature of the adsorption encountered here. It has been shown that the data obtained fits in the adsorption equation derived by Krishnamurti (a = K/1 + αe−βc) far better than the adsorption isotherms of Freundlich and Langmuir.
The view that the interaction between bacteria and the charcoal and kaolin particles is an adsorption process is supported by several independent observations,
A marked increase of the maximum adsorption of bacteria has been observed with the lowering of temperature and a straight line is obtained by plotting the maximum amount of adsorption of bacteria against 1/T.
The specific and selective nature of the adsorption of bacteria by charcoal and kaolin has been successfully applied for evolving a new technique for the separation of bacteria from mixtures (e.g., B. subtilis from Staphylococci). It is hoped that this method when standardized will be a useful addition to bacteriological technique.
pp 92-98 August 1951
The sclereids in the cleared mature leaf ofDiospyros discolor show two types of distribution with reference to veinlets; either terminal or diffuse. Ontogenetic studies have, however, revealed that the initials of the seemingly terminal sclereids arise away from the procambial strands. They are in fact transformed cells of the spongy parenchyma and the terminal appearance is due to juxtaposed development. Sclereids should not be designated as “terminal” merely on the basis of their position in the mature leaf unless this is compared by an ontogenetic study.
pp 99-108 August 1951
pp 109-113 August 1951