Collectanea de Diversis Rebus: Addresses and Papers. Eade Peter

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СКАЧАТЬ style="font-size:15px;">      Mr. Darwin speaks of a large kind of Tortoise which is reputed to be able to walk at the rate of sixty yards in ten minutes; i. e., three hundred and sixty yards in the hour, or four miles a day. I have twice timed the rate of progress of one of my Tortoises. Once it walked ten feet in the minute, and another time twenty feet in the minute. This latter is at the rate of twelve hundred feet, or four hundred yards, in the hour; or of a mile in between four and five hours. This truly is not quite the ordinary rate of the hare’s progress, but I think they can cross a certain small distance of ground much more rapidly than we should at first suspect.

      Once more. These creatures distinctly grow in size from year to year. Our two measure respectively seven and seven and a half inches in length. And they must have elongated fully an inch in the three and four years of our possession.

      I weighed them this year, on May 29th, soon after their waking up for the summer, and again on September 8th. They weighed in May, 2 lbs. 7½ ozs. and 2 lbs. 3½ ozs.; a fortnight ago they weighed 2 lbs. 10 ozs. and 2 lbs. 5 ozs.; having thus gained in weight through their summer feeding 2½ ozs. and 1½ ozs. respectively.4

      When the due period arrives in which they naturally bury themselves, and so surround themselves with earthen bulwarks, and then retire for the winter into their carapace castles, we put them down into a cupboard in the cellar.

      Mr. White remarks that his Tortoise did not bury itself into the ground before November 1st, but ours are cold and torpid, and quite ready to hybernate by the first week in October. Probably the different latitude and longitude of Selborne and Norwich may account for this difference of time.

      In this cellar cupboard, the Tortoises remain until the end of April, when, though still dull and stupid, the weather is getting sufficiently warm for them to enjoy the sun for a portion of the day. But the frosts and cold of this period of the year are still dangerous. And a relative of mine lost both of his old friends (who for years had taken care of themselves in the winter in his garden) during the cold weather of this spring, after they had duly survived the far greater cold of the winter in the ground places in which they had buried themselves.

      From October to April – fully seven months – they rest from their labours of eating, of breathing, shall I say, of thinking? (or nearly so, for they occasionally stir a little, and are found to have moved a little from under their straw). But they neither eat nor drink, nor see light, nor (I believe) open their eyes. And when touched during this time they feel of a stony coldness, and certainly appear to have none of their faculties in operation.

      But with the warmer weather, they again gradually resume the precise habits of the preceding year. Gradually, their bright little eyes resume their intelligence; their memory re-awakens; and they return to the ways, and the habits, and the places of the preceding season, as if their sleep of seven months were but a single night, and last summer verily but as yesterday.

      They are in many respects both curious and remarkable animals. We find them to have enough of intelligence, enough of quaintness, and apparently enough of affection, to give them considerable interest in the eyes of their owners, and to raise them out of the level of despised reptiles. Whilst their remarkable construction, and mysterious power of hybernation, render them specially worthy of study and contemplation.

      These specialities and peculiarities must be my much-needed excuse for having troubled you so long with these few details of their personally observed habits and ways.

       IV.

       A FURTHER NOTE UPON TORTOISES. 5

      In the year 1886 I read before this Society a paper in which I recorded some of the observed habits and peculiarities of a pair of Tortoises which I had then kept in my garden for three and four years respectively. This paper was afterwards published in our Society’s “Transactions” (Vol. iv. p. 316), and will probably be remembered by some of our members.

      I would like this evening to say a few further words upon these creatures, which are still living and in my possession – more particularly with reference to their rate of growth and increase.

      The two Tortoises have now been in my possession ten and nine years respectively. Six years ago I reported to this Society that they measured, the one 7½ and the other 7 inches in length. Now at the end of six further years their antero-posterior measurements are 9½ and 9 inches respectively – the measurements being made from before backwards over the convex surface of the carapace. They have, therefore, each of them, thus measured, increased exactly two inches in length in the last six years, or at the rate of exactly one-third of an inch per year.

      (The under flat surface of the shell now measures 6½ and 6¼ inches from before backwards. These Tortoises are said not usually to exceed 10 inches in entire length.)

      Then as to their weight. I have now kept an exact record of their respective weights in the spring and autumn of each of the past seven years, i. e. their weight on commencing to hybernate in October or November, and again their weight on returning afresh to light and more active existence in April or May of the following spring. And it is interesting to notice how almost continuously they have increased both in size and weight; and also how corresponding are the alterations, or otherwise, in the consecutive years, both of spring and autumn, of the two animals.

      In my former paper, I mentioned that during the summer months of 1886, when I first weighed them, i. e. from May to September, my Tortoises had gained in weight, the one 2½ ounces, and the other 1½ ounces; whilst each of them became lighter in the following winter by 2½ ounces. Since that time the spring and autumn weighings have been regularly continued, and the result is shown in the following table.

      In the seven years, therefore, 1886 to 1892, the larger Tortoise has increased in weight from 2 lbs. 10 ozs. to 3 lbs. 3½ ozs.; and the smaller Tortoise from 2 lbs. 5 ozs. to 2 lbs. 14½ ozs., giving a total increase of weight in this period of exactly 9 ounces for each animal, or an average annual increase of about 1 ounce and 5½ drachms (avoirdupois).

      The general result also of the above weighings is to show that, in average seasons in England, these creatures gain from 2 to 2½ ounces in each summer, and lose again a varying but considerable portion of this increase during the ensuing six or seven months of hybernation; but, on the whole, showing an average gain of a little more than one ounce in the year – the average gain of weight per month in summer working out at about 6 or 7 drachms, with an average loss in the winter months of about 4 or 5 drachms per month. This last fact scarcely agrees with Cuvier’s statement that “during winter.. their loss of substance amounts almost to nothing.”

      It will be noted that the foregoing table shows certain variations in the increases and decreases of weight in the several years; also that in two of the years there was but little change between the autumn and spring weights – this period of stagnation occurring in both animals simultaneously. Probably several causes for this were at work, but I have little doubt that the variability of our English seasons is by far the largest factor in the case; and that the variations in the gainings and losings of the different summers and winters depend very largely upon the special character of these seasons. Thus, when the summer months are hot the Tortoises eat much more abundantly and constantly, and consequently put on (or rather put inside their skeletons) much more flesh than in colder seasons. On the contrary, a warm autumn, with the temperature not sufficiently cold to make them go early and thoroughly to sleep, must conduce to greater loss, or rather waste, of their flesh, for it is well known that these animals cease to eat many weeks before they finally retire to rest for the winter; and necessarily during this period, especially on sunny СКАЧАТЬ