Volume 53, Issue 4
April 1961, pages 157-216
pp 157-165 April 1961
This paper describes the X-ray diffraction studies carried out on a large number of present-day, as well as fossil diatom frustules. From the diffraction patterns given by the various specimens, it has been concluded that the silica present in diatom frustules is not in an amorphous or sub-colloidal state as was spposed by previous workers but that it is crystalline α-quartz. Although crystalline α-quartz is present in present-day diatoms, the degree of crystallisation is much less than in the fossilized specimens. In addition to the crystalline quartz content, there is present in all diatoms an organic component which might possibly be a protein. In the present-day diatoms this organic component occurs in considerable proportion so that its X-ray diffraction pattern tends to mask the pattern due to crystalline α-quartz. On fossilization, however, a considerable amount of the protein content is lost, while the silica content becomes more predominant, and more and more crystalline with time. Evidence for the occurrence of pectin in diatoms is also presented.
pp 166-172 April 1961
The zygote ofEpithema carnosum divides by a transverse wall. The terminal cell undergoes division by a vertical wall. The next division in the daughter cells occurs in the same plane but at right angles to the first-formed partition. During this division the partition walls meet the original vertical wall at right angles. After the completion of the two divisions, cell readjustments tend towards a state of minimal potential energy. The quadrant cells at this stage come to possess walls disposed as in a group of four soap bubbles in contact and in a state of stable equilibrium. The possible conjoint operation of physical and biochemical forces during the early divisions of the zygote is discussed.
pp 173-181 April 1961
Fish fillet when dipped in CTC solution at 20 p.p.m. picks up the antibiotic only on the surface or just below it. It is not found in the innermost core of the muscle. The absorption of the CTC even on the surface is not quite uniform throughout a fillet. White muscle of a fish picks up the antibiotic more readily than the fatty layers or the brown-coloured portions of the muscle.
Washing the fillet with water prior to its preparation for the table removes a considerable portion of the antibiotic, the amount so removed ranging from 54 to 62% of the original amount.
Heating the antibiotic-treated fish with water at 70°C. and above for periods of more than 10 minutes or keeping the fish at 98°C. even for a short while completely inactivates or destroys the antibiotic. Frying and grilling the fish destroys the antibiotic to the extent of 87 to 100% of the original quantity present. The maximum quantity found in the latter cases was only 0·12 p.p.m. which can be considered to be innocuous.
pp 182-186 April 1961
pp 187-203 April 1961
pp 204-216 April 1961