Volume 63, Issue 3
March 1966, pages 105-163
pp 105-109 March 1966
pp 110-116 March 1966
pp 117-125 March 1966
Like all other polychaetes,M. gravelyi also swells when exposed to hyposmotic media. But the extent of increase was considerably low. In this worm, as in other polychaetes, the initial increase and the final volume attained are a function of the external medium. Both the final volume and the initial increase being very low inM. gravelyi, reduction in permeability is, perhaps, the maximum.
pp 126-132 March 1966
Formation of leaf tumours in an interspecificTriticum hybrid has been reported.
These tumours were located only along the veins of the leaves.
Histological study has revealed that these tumours were formed as a result of the swelling of the vascular tissue itself.
The actual cause for the development of these tumours is not yet known.
pp 133-144 March 1966
pp 145-151 March 1966
The account deals with the effect of photo-function (a term to indicate the variable sensitivity to photoperiod of a shoot during growth) of transplanted rice. VarietiesTKM. 6 andADT. 20 were used as test crops. Post-planting photo-function is controlled by age of seedling. Post-planting effect is varietal and continuous on the life of the plant. The sub-optimal sensitivity of the plant to light increases with the age of the seedling and suppresses growth and development of the early shoots remarkably. It is recommended that by choosing the age of the seedling for planting, the plant can be adapted to a dull or bright weather ahead and younger the seedling, better the response to day length.
pp 152-160 March 1966
The genusCentaurium is represented in Amritsar District by three types of plants, distinguishable chiefly on the basis of flower-colour. The three races possess different chromosome numbers: white,n=18; purple,n=27; and cosmos,n=28.
A new basic number, 9, has been found to exist in the genus.
The white-flowered (4x) and purple-flowered (6x) races are, in all probability, alloploid in character. The exact nature of the cosmos-flowered race (n=28), however, is not known at present. It may either be an octoploid on the basic number 7, or a secondary polyploid from the hexaploid ofx=9 (2n=56=6x + 2=54=2). All the three colour-forms have been referred toE. ramosissima Pers. now calledC. pulchellum (Sw.) Druce by most taxonomists. However, the present investigation reveals that none of the races conforms strictly to this or to any other Indian species described by Hooker (1883). It appears that all or most of these species have arisen after extensive interspecific hybridization, which has resulted in a complete reticulation of characters. Furthermore,C. pulchellum in itself is a complex withn=10, 18, 20, 27, 28. In order to have a clear picture of the relationships of the Indian formsvis-a-vis their European counterparts, it is essential to conduct a well-planned biosystematic investigation based on samples from the entire range.
The taxonomic tangle and synonymy needs to be clarified by reference to the type material.
pp 161-163 March 1966
1. Method for determining Mitotic peak time inStigeoclonium amoenum Kütz has been described.
2. A low-background-level of about 0·5% cells showing mitosis almost throughout the 24 hours has been observed.
3. The Mitotic peak when there was 12 hours light followed by 12 hours darkness occurred one hour after the beginning of the light period (4% cells showed mitosis).