| The following edited passage is taken | | excited into movement by a solution of |
| from Insectivorous Plants | 55 | the carbonate so strong that it would |
| by Charles Darwin on leaves and | | paralyze ordinary leaves and cause no |
| temperature. | | inflection. |
| | | |
| In my observations on Drosera | | The exposure of the leaves for a few |
| rotundifolia, the leaves seemed to be | | minutes even to a temperature of 145 °F |
| more quickly inflected over animal | 60 | does not always kill them; as when |
| substances, and to remain inflected for a | | afterwards left in cold water, or in a |
5 | longer period during very warm than | | strong solution of carbonate of ammonia, |
| during cold weather. I wished, therefore, | | they generally, though not always, |
| to ascertain whether heat alone would | | become inflected; and the protoplasm |
| induce inflection, and what temperature | 65 | within their cells undergoes aggregation, |
| was the most efficient. Another | | though the spheres thus formed are |
10 | interesting point presented itself, | | extremely small, with many of the cells |
| namely, at what degree life was | | partly filled with brownish muddy |
| extinguished; for Drosera offers unusual | | matter. In two instances, when leaves |
| facilities in this respect, not in the loss | 70 | were immersed in water, at a lower |
| of the power of inflection, but in that of | | temperature than 130 °F, which was then |
15 | subsequent re-expansion, and more | | raised to 145 °F, they became during the |
| especially in the failure of the | | earlier period of immersion inflected, but |
| protoplasm to become aggregated, when | | on being afterwards left in cold water |
| the leaves after being heated are | 75 | were incapable of re-expansion. |
| immersed in a solution of carbonate of | | Exposure for a few minutes to a |
20 | ammonia. | | temperature of 145 °F sometimes causes |
| | | some few of the more sensitive glands to |
| As the hair-like tentacles are extremely | | be speckled with the porcelain-like |
| thin and have delicate walls, and as the | 80 | appearance; and on one occasion this |
| leaves were waved about for some | | occurred at a temperature of 140 °F. On |
| minutes close to the bulb of the | | another occasion, when a leaf was placed |
25 | thermometer, it seems scarcely possible | | in water at this temperature of only 140 °F, |
| that they should not have been raised | | and left therein till the water cooled, |
| very nearly to the temperature which the | 85 | every gland became like porcelain. |
| instrument indicated. From the eleven | | Exposure for a few minutes to a |
| last observations we see that a | | temperature of 150 °F generally produces |
30 | temperature of 130 to 30 °F never causes the | | this effect, yet many glands retain a |
| immediate inflection of the tentacles, | | pinkish color, and many present a |
| though a temperature from 120 °F to 125 °F | | speckled appearance. This high |
| quickly produces this effect. But the | 90 | temperature never causes true inflection; |
| leaves are paralyzed only for a time by a | | on the contrary, the tentacles commonly |
35 | temperature of 130 o 35 °F, as afterwards, | | become reflexed, though to a less degree |
| whether left in simple water or in a | | than when immersed in boiling water; |
| solution of carbonate of ammonia, they | 95 | and this apparently is due to their passive |
| become inflected and their protoplasm | | power of elasticity. After exposure to a |
| undergoes aggregation. This great | | temperature of 150 °F, the protoplasm, if |
40 | difference in the effects of a higher and | | subsequently subjected to carbonate of |
| lower temperature may be compared | | ammonia, instead of undergoing |
| with that from immersion in strong and | 100 | aggregation, is converted into |
| weak solutions of the salts of ammonia; | | disintegrated or pulpy discolored matter. |
| for the former do not excite movement, | | In short, the leaves are generally killed |
5
| whereas the latter act energetically. A | | by this degree of heat; but owing to |
| temporary suspension of the power of | | differences of age or constitution, they |
| movement due to heat is called by Sachs | 105 | vary somewhat in this respect. In one |
| heat-rigidity; and this in the case of the | | anomalous case, four out of the many |
| sensitive-plant (Mimosa) is induced by | | glands on a leaf, which had been |
50 | its exposure for a few minutes to humid | | immersed in water raised to 156 °F, |
| air, raised to 120 °F -122 °F. It deserves | | escaped being rendered porcellanous; |
| notice that the leaves of Drosera, after | 110 | and the protoplasm in the cells close |
| being immersed in water at 130 °F, are | | beneath these glands underwent some |
| | | slight, though imperfect, degree of |
| | | aggregation. |