Volume 45, Issue 2
February 1957, pages 27-94
pp 27-31 February 1957
1. Cells ofL. casei grown in presence of penicillin are found to contain decreased amounts of PNA, DNA being unaffected.
2. PGA by itself and, more effectively, in presence of vitamin B12 exerts protection against the inhibitory action of the antibiotic on growth as well as on PNA formation.
pp 32-42 February 1957
1. The anatomy of the antennæ of eight species of sugarcane moth borers,viz., Scirpophaga nivella, Chilo zonellus, Chilo tumidicostalis, Chilotrœa infuscatellus, Chilotrœa auricilia, Bissetia steniellus, Sesamia inferens andEmmalocera depressella has been studied and described in details.
2. Well pronounced phenomenon of sexual dimorphism has been observed to be present in cases ofE. depressella (Anerastiinœ-Pyralidœ),Sesamia inferens (Agrotidœ-Noctuidœ) and also to some extent inBissetia steniellus (Crambinœ-Pyralidœ).
3. It has been observed that in species where sexual dimorphism is well pronounced the antennæ are of great diagnostic and systematic value for the identification of those species.
4. The present studies have revealed that the number of antennal segments in a particular species is never constant but each species has its particular range within which the number of antennal segments may vary. It has also been observed that generally the number of antennal segments in males is higher than in the females.
5. The data presented in the above-mentioned two Tables I and II was statistically analysed and it revealed that the difference between both means of all these species except in cases ofS. nivella with that ofC. infuscatellus and that of their opposite sexes was significant at 5% level.
pp 43-63 February 1957
An attempt has been made to study the chemical partition of nitrogen in eleven species of seaweeds belonging to the three major groups, Chlorophyceæ, Rhodophyceæ and Phæophyceæ. The seasonal variations in the total organic, water-soluble, volatile, protein and non-protein nitrogen contents were followed by analysing regular monthly collections of the algæ. The importance of each of the fraction in the metabolism of the algæ has been discussed. It is observed that the seaweeds are poor in their total nitrogen content, the values never exceeding 2% on the dry basis. In species likeG. lichenoides the total nitrogen content shows an inverse ratio to that of the agar content. Protein nitrogen is less in young plants, while in the mature plants it accounts for more than 75% of the total organic nitrogen. Water-soluble and volatile nitrogen content also follows the total nitrogen giving maximum values in September–December and minimum in July.
The amino acid composition of two sets of collections representing two distinct growth stages has also been studied quantitatively. It is observed that although the protein-nitrogen content varies substantially between the young and the mature plants the amino acid composition remains almost identical.
The chromatographic method employed in the quantitative estimation of the amino acids has been outlined.
pp 64-76 February 1957
1. If frog’s stomach muscle is immersed in hypotonic sucrose solution, it maintains its excitability for about 24 hours, after a preliminary depression. The responses in the sucrose solutions may be several times bigger than in saline.
2. The spontaneous contractions of the muscle in sucrose solution are accompanied by action potentials.
3. When the muscle is contracting strongly in the sucrose solution, the sodium content (of the muscle) is negligible thus showing that sodium is not necessary for the production of mechanical and electrical changes.
4. When the muscle has acclimatised to sucrose, sodium has a depressant action, showing that the mechanical and electrical responses of the muscle are not due to any retention of sodium in the interspaces between the fibres.
5. The muscle also responds as in sucrose solution, if all the sodium of the saline is replaced with ammonium, potassium, calcium, strontium and magnesium. This suggests that the membrane of this tissue is comparatively resistant and hence this muscle can be deprived of sodium, and still maintain its excitability.
pp 77-85 February 1957
The object of this investigation was to study the total phosphorus content of the inshore waters with a view to understanding the phosphorus cycle in the sea. Seasonal variations in the total and soluble inorganic phosphorus concentration in the inshore waters of the Malabar Coast, a region highly productive from the fisheries point of view, was studied over a period of one year during 1954 to 1955 near West Hill, Calicut. Preliminary observations on the data collected have been presented in this account which also include some information on the total phosphorus content of the waters of the east coast near Mandapam. Sea-waters off Calicut were found to be rich in total phosphorus which varied from 1·2 to 9·5µg.-ats. P/1. in the surface layers. Soluble inorganic phosphorus accounted for only 8·5 to 37·0% of the total except in the month of June when the onset of the S.W. monsoon is followed by a steep rise in the total as also the inorganic phosphate. It is probable that release from the bottom muds as a result of the severe agitation of the water column in the monsoon months may explain the high levels of phosphorus compounds. Large-scale mortality of bottom dwelling animals may also play some part in this connection.
A comparative study of the levels on the east and west coasts confirms the usefulness of total phosphorus determinations as an index of the potential fertility of different regions.
pp 86-90 February 1957
pp 91-94 February 1957
A chromatographic method for qualitative and quantitative determination of gibberellic acid inF. moniliforme infected rice plants has been described. The concentration of gibberellic acid and the area of the band on a circular paper chromatogram bear a linear relationship. The results indicate a greater accumulation of gibberellic acid in shoots than roots of the rice plant var. MTU 9, susceptible to the fungus.