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Toxicity of Seed
| No. | Material used. | Dose per Kilogram, in Grammes. | Result. | Estimated Percentage of Tutin in Seed. |
|---|---|---|---|---|
| 256c | Sample I | 3.7 | Death in three hours | 0.16 |
| 267 | Sample II | 3.7 | Slight, if any, symptoms | |
| 270 | " | 4.0 | Distinct minor symptoms | 0.14 |
| *295 | " | 4.3 | Death in about three hours | 0.16 |
| 272 | " | 4.5 | Symptoms more marked than in exp. 270 | 0.12 |
| 274 | " | 5.0 | Severe symptoms, but recovered | 0 11 |
| 282 | " | 6.5 | Death in three hours | 0.10 |
| 396 | Green seed | 6.0 | Death in one hour and a half | 0.125 |
The percentages of tutin in these experiments have been calculated from the results of previous work by Fitchett and other experiments by the writer. The standards adopted for rabbits were that a dose of 5 milligrams per kilogram produces no marked symptoms; 6 milligrams produces symptoms in one hour and a half, and is ultimately fatal; 7.5 milligrams produces symptoms in about half an hour, and death between one and two hours.
Sample I of the seed was used in only one experiment, and in that case was more toxic than sample II. It occurred to me that this might be due to a difference in the toxicity of green seed as compared to ripe, for, owing to the method of collecting it, sample II contained more ripe seed than sample I. Fortunately, although it was late in the year (May), I was able to procure locally sufficient green berries to put the matter to a test.
At first it seemed impossible without serious loss of time to mechanically separate the small unripe seeds from the green fleshy petals, and after separating enough to find the percentage of seed present (18.2) the whole unripe fruit was administered in the form of a watery suspension. This gave the following results: 27 grm. fruit per kilogram caused death in forty-five minutes; 14.4 grm. in ninety-five minutes; 10 grm. in two hours and a half. As 10 grm. fruit contained only 1.8 grm. seed, it followed that either the unripe seed contained a very large amount of tutin, or that, at this stage, it was also present in the fleshy petals. To decide this point it was necessary to obtain a clean sample of unripe seed, and after several attempts the following method was found to be successful: Berries were dried in air at a moderate temperature and rubbed between the fingers; by this means the seeds were isolated from the remainder. The material was then put,
[Footnote] * This animal had been used for exp. 274, and had then had its thyroid gland removed, about four weeks before being used for exp. 295
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in small quantities at a time, into a mixture of naphtha and chloroform of such a specific gravity that the seeds floated while all the debris sank, and by skimming off and drying the seed a fine clean sample was obtained. When administered to a rabbit this gave the result shown in the table, exp. 296—viz., the percentage of tutin was no greater than the average. It follows, therefore, that at an early stage in the formation of the berry the fleshy petals contain as much tutin as other green parts of the plant—in fact, the percentage works out to the same (0.06) as was found in the green shoots of Coriaria ruscifolia.
It would be interesting to be able to follow the fate of the tutin in the petals. Is it transformed in situ into a constituent of the innocuous juice, or is it transported to other parts of the plant? If the former takes place, one is tempted to believe a ferment might be found capable of affecting the transformation, and such a ferment would be of value in destroying tutin while still in the paunch of stock poisoned by tutu. So far I have not been able to get any evidence of the presence of such a ferment.