OCR Text |
Show 1881.] OF THE INDIAN PYTHON. 961 incubation, in the early part of July, when she left her eggs for a few hours, returning to them again however and coiling herself up as before, though now the regularity of her folds was not so great as it had been previously. On July 18th (that is, after a period of forty-three days from the date of laying), as the eggs were evidently decomposing, they were removed; and their state on examination was found to be very similar to that observed by Mr. Sclater on the previous occasion. Several of those examined showed no traces of having been impregnated; at least, no signs of any development inside remained; one or two, however, contained embryos, one of which was about 11 inches long, and had its scales well developed. From the discrepancies existing between the observations of Valenciennes and those made here previously on the temperature of the incubating Pythoness, it seemed highly desirable to utilize the opportunity afforded by this last instance for a further and more extensive series of observations on the phenomenon in question. Mr. Zambra, of the well-known firm of Negretti and Zambra, w ho had himself taken part in the observations made in 1862, was kind enough to give m e his most valuable aid and assistance in this investigation. H e not only supplied us with excellent self-registering thermometers of the newest pattern and most delicate make, but was also kind enough to attend regularly-often, I fear, at considerable inconvenience to himself-to superintend and take the necessary readings. With the assistance of M r . Bartlett, Mr. Clarence Bartlett, and the keeper of the reptiles, J. Tyrrell, M r. Zambra and I were thus enabled to take a very considerable number of observations on the point in question, with instruments of a more accurate kind than had been available for our predecessors. Our first observations were taken on June 14th, about nine days after the eggs were laid; and they were continued thence without intermission, at intervals of two or three days, till the eggs were removed on July 18th. The readings were always taken about the same time of day, from 12 to 2 o'clock, in order to avoid any differences that might be due to the diurnal variation of temperature. Following Mr. Sclater's example, we took a double series of observations, one set on the incubating female, another on the male of the same species, which, after it had been removed from the female when the eggs were laid, was kept in the cage next to that of the female under conditions practically identical. The temperature of the Snakes was ascertained, first by placing the thermometer on the surface of their bodies, and then by placing it between the folds of their coils. In each case their bodies were covered by the blankets under which they usually rest; and, as far as possible, the different readings, of which we usually took three in each set, were obtained in as many different places in the coils, one towards the centre, the others more towards the outside. The temperature of the air was taken by suspending a thermometer a little way above the floor of the cages; that of the gravel in the cagea by burying the bulb of the thermometer in the gravel, in the same position in each cage, and over the hot-water pipes which run beneath the floors of the cages. PROC. ZOOL. Soc-1881, No. LXII. 62 |