Volume 1, Issue 11
May 1935, pages 677-815
pp 677-685 May 1935
pp 686-692 May 1935
Evidence has been adduced to show that during autolysis of barley powder no amylokinase is formed.
The increase in amylase activity on autolysis is solely due to increased liberation of β-amylase of barley.
pp 693-704 May 1935
pp 705-709 May 1935
pp 710-713 May 1935
Our revised interpretation ofRajmahalia regards it as aninverted funnel-like organ (possibly part of a deciduous andrœcium) fallen from the top of a Bennettitalean receptacle and bearing on its inner surface the impress of the seeds and interseminal scales once pressed against it, but now no longer preserved.
Roughly there are as many scales as ovules, and each scale more or less completely envelopes an ovule, especially on its outer (centrifugal) side. This may suggest an early stage in the formation of a closed carpel of the angiospermous type.
pp 714-728 May 1935
The full development ofSalmacis bicolor, a tropical form has been traced both in regard to the external characters and several internal features.
The amnion has been shown to arise very early in development.
The development of the larval skeleton has been traced.
The metamorphosis and the post-larval stages have been described.
The absence of sexual periodicity inSalmacis bicolor has been proved.
pp 729-735 May 1935
pp 736-753 May 1935
The march of assimilation from day to day in a young leaf for twenty days—the period of physiological activity of a radish leaf in the laboratory—is deduced from the separate time-assimilation curves of mature and old leaves.
Under the natural pressure of carbon dioxide in the atmosphere, assimilation of radish leaves increases continuously upto 29°C. more or less in conformity with the Van’t Hoff’s law, the coefficient of increase being 2·26.
The maximum assimilation attainable under the atmospheric conditions of carbon dioxide is reached at 30°C.
From 30 to 34°C. the first observed value of assimilation attained is of the same order but at and beyond 30°C. this initial value of photosynthesis abates in successive hours.
While the first evidence of time factor is available at 30°C. its pronounced influence is manifested not till 37°C. when the disparity between the first and second hourly reading is striking.
At 29°C. it is possible to reach a higher sustained pitch of assimilation in time by increasing the partial pressure of carbon dioxide in the environment.
Assimilatory activity in the radish leaf becomes extinct at a temperature of 47·4°C. and does not commence at a temperature lower than 12·6°C. in these regions. This behaviour is contrasted with that of Cherry Laurel, recorded by Matthaei working in the temperate regions who found the threshold value for photosynthesis to be −6°C., and ascribed to the ecological adaptation of the plants to higher temperatures in these regions.
pp 754-762 May 1935
At the normal atmospheric pressure of carbon dioxide the intensity of assimilation increases measurably with the intensity of illumination upto 68,760 metre candles in radish leaves in the sub-tropics.
At a ten time atmospheric concentration of carbon dioxide the rate of assimilation continues to increase with the intensity of illumination to a slightly higher illumination intensity of 72,197 metre candles.
Depression in the photosynthetic activity of radish leaves appears to occur for the first time at a light intensity more than twice the average sunlight in the winter months in these regions. An appreciable time factor sets in at a light intensity of 1,80,000 metre candles.
This depression in the photosynthetic rate appears to be connected with the inactivation of chloroplasts and is capable of reversal under reduced light intensity provided the exposure to the higher light intensity has not been prolonged.
The threshold light intensity for photosynthesis is in the neighbourhood of 4,000 metre candles for radish leaves in these regions. The minimal and optimal cardinal points herein mentioned though characteristic of the winter season in the sub-tropics should not necessarily apply to the temperate regions where the plants are adapted to lower intensities of light in contrast to the high illumination conditions obtaining in these regions.
pp 763-777 May 1935
From a cytological investigation of the somatic chromosome cycle of Safflower the following summary and conclusions are drawn:—
The 2n number of the chromosomes is ascertained for the first time in this plant, as 20 from several counts of the somatic metaphase plates.
The stages of somatic cycle are described in detail and an interlacing dual aspect has been shown to exist for the chromosomes in almost all the stages of the somatic cycle.
The three theories of chromsome structure are briefly reviewed and discussed.
The dual, twisted aspect of prophase chromosomes is demonstrated and discussed with special reference to the chromomeric hypothesis of chromosome structure. It is concluded that the chromomeric appearance seen in the prophase threads is due to the optical effects of viewing a deeply stained interlaced thread under the microscope, especially when stain is retained in the diamond spaces formed by the twists of the threads.
Splitting of the daughter chromosomes is shown to occur in the preceding division—mostly in late prophase or early metaphase—for the separation in the present division.
The mode of splitting or the line of cleavage in the daughter chromosomes is discussed and the conclusion is drawn that the assumption of a spiral split is more in agreement with the sequence of events than that of a straight split.
Duality and twisted aspect of anaphase chromosomes are demonstrated and their significance in relation to the “Precocity hypothesis” explaining the difference between mitosis and meiosis, is described and discussed. It is concluded that the difference between the two is not a delay in the split in the prophase of meiosis as assumed by the above hypothesis, but a complete suppression of the prophase split in the heterotypic division of meiosis.
pp 778-815 May 1935
A general account of the methods of pan cultivation practised in the Central Provinces and Berar is given.
A detailed account of the foot-rot diseases of pan caused byPhytophthora and a new species ofPythium, of the leaf-rot caused byPhytophthora and of the anthracnose disease caused byColletotrichum spp. is given.
A short account of the foot-rot diseases suspected to be caused bySclerotia Rolfsii, Rhizoctonia bataticola andR. Solani is given.
ThePhytophthora causing the foot-rot and leaf-rot disease is considered to beP. parasitica var.piperina, n. var.
ThePythium causing the foot-rot disease is namedP. piperinum n. sp.
Remedial measures for the control of the foot-rot, leaf-rot and anthracnose diseases are described.