Art. XXXVI.—Observations on Naultinus pacificus, Gray.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 5, 1872, Page 307

Art. XXXVI.—Observations on Naultinus pacificus, Gray. By F. J. Knox, L.R.C.S.E. [Read before the Wellington Philosophical Society, 29th January, 1872.] On the 20th October, 1869, a neighbour brought me a lizard incarcerated in a gin-bottle. The prisoner was extremely restless, and my friend stated as a caution that when captured it was very lively, offering a spirited resistance. After a week's imprisonment, on 28th October, I determined to improve the condition of the prisoner, having previously prepared a more suitable habitation for him, but having to break the bottle, in the struggle the tail was detached from the body precisely at the apparent junction with the sacrum, at what is generally called the “setting on of the tail.” On being secured in his new residence (still, of course, a prisoner) he did not appear conscious of the loss of his caudal extremity, but surveyed every corner for the means of escape. As bearing on the feeding habits of this lizard I may state that small portions of flesh were put beside him, and an active blue-bottle fly having fancied the raw meat was suddenly struck by the lizard with the rapidity of lightning, and with a force which crippled it. During his efforts to regain his liberty he frequently, I could observe, licked with his tongue the entire surface of the face, including the eyes. Three days after the accident the lizard appeared dull, but when disturbed still only anxious to obtain his freedom. The stump where the tail was detached was swollen and evidently painful. He refused all food, but was still active till the seventh day, and on the eighth died. On dissection he proved to be a male, the generative organs not active. Skeleton. Vertebræ—body 26 sacral 8 caudal 29 Total 63 Ribs 26 Weight, recent, 156 grs.; weight of skeleton, 18 grs.; and of soft parts 138 grs. It has been stated that when the tail of a lizard has been amputated the detached portion will be reproduced in its entirety. Scientific men will naturally require minute details of such an experiment, with reliable authority. We have shown in the preceding article that the tail of the Naultinus pacificus was separated (not amputated), and it will be seen that the place where the separation took place presented no appearance of laceration or cutting, with the exception of the spinal cord. The greatest care and attention was bestowed upon the lizard, but unmistakeable symptoms of the injury exhibited themselves, and death rapidly followed.

I have examined a specimen of a lizard in the Colonial Museum presenting the phenomena of two tails nearly of equal size, and it has appeared to me that the possession of a supernumerary tail in this case may be attributed to the class of monstrosities. We know that lizards are developed within the isolated egg, and it is well understood that monstrosities are comparatively common in oviparous animals. A question of much interest thus remains still to be solved, viz., Is the tail reproduced in its entirety, when the whole or even a portion of it is forcibly or accidentally removed? In the dead specimen described by me in a previous article*Trans. N.Z. Inst. Vol. II., p. 20. I found the continuation of the medulla spinalis left the canal without the least disturbance, and when thus drawn out as it were, it presented a series of swellings (ganglia) exactly corresponding to the number of the vertebræ. My theory, therefore, was that any regeneration of the tail would be mere integumentary reproduction. I have shown in the present paper that, when violently detached in the living animal, the medulla spinalis does not leave the canal, but is torn across, the detached portion remaining in the tail. My specimen forming the subject of the present memoir died on the eighth day after the accident, and the eighteenth day after the capture and confinement, but whether from the want of nourishment or the loss of his tail it is impossible to say.