The photosynthesis of naturally occurring compounds.—III. Photosynthesis in vivo and in vitro
The evidence adduced in the two preceding communications leads to the belief that the direct photosynthesis of complex carbohydrates in a single operation from carbonic acid has now been achieved in the laboratory. There still remains, however, the question as to how far the results take us in the e...
| Published in: | Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character |
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| Format: | Article in Journal/Newspaper |
| Language: | English |
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The Royal Society
1927
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1098/rspa.1927.0133 https://royalsocietypublishing.org/doi/pdf/10.1098/rspa.1927.0133 |
| Summary: | The evidence adduced in the two preceding communications leads to the belief that the direct photosynthesis of complex carbohydrates in a single operation from carbonic acid has now been achieved in the laboratory. There still remains, however, the question as to how far the results take us in the explanation of the natural process as it occurs in the living leaf. It must be admitted that the natural process has ever presented many difficulties, and in view of the foregoing results the problem of its explanation is one of peculiar interest. In the first place, we may refer to the difficulty arising from the complete absence of ordinary formaldehyde in the living leaf. The elegant work of Willstätter, proving that the molecular ratio of the carbon dioxide assimilated and the oxygen transpired is unity, offers a very definite proof that the first product in the photosynthesis is formaldehyde, and, in consequence, the fact of its entire absence from the leaf during photoassimilation of carbon dioxide was very difficult to understand. This difficulty has been completely eliminated by our results. Theoretical considerations based on the formation of activated carbonic acid as the initial stage in the process lead to the view that activated formaldehyde is then produced, which at once undergoes polymerisation to give the hexoses. De-activated or ordinary formaldehyde should not, therefore, take part in the reaction and, in consequence, should not be found at any stage. These theoretical deductions have been proved to be correct, since in the photosynthetic production of carbohydrates in vitro the complete absence of ordinary formaldehyde has been proved. So far as this fact is concerned there is agreement between the laboratory and living processes. |
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