Environmental control of cell morphology in desmids
The variability of the desmids was quite interesting to note that when the conditions such as temperature and illumination were altered, there was not only an increase in the abnormal forms but the number of the adherent cells were also more. This abnormal behaviour of the species was more or less directly proportionate to the altered status of these factors in culture. It was thus quite clear that due to an increase or decrease in temperature and light intensity, quite a number of variants were produced. Sometimes the cells departed so widely from the specific characteristic that one could mistake them as belonging to different taxa. It may be that under unfavourable conditions of growth the mechanism of cell division was disturbed lowering thereby the percentage of mitosis and finally leading to the tendency of morphological aberrations. Consequently, these observations induced to study the various species of desmids under different experimental conditions to find out the range of morphological variation in cultures because the feature which more than any other, has attracted algologists to study desmids especially placoderms is their considerable morphological variability. Morphological variations under different cultural conditions have been studied and it is presumed that the cell types are capable of maintaining their narrow specificity, which is genetically controlled under favourable conditions only, but, whenever, there is a change in environmental set-up, it has resulted in upsetting the metabolic behaviour leading to abnormal forms.