OCR Text |
Show 1875.] REV. S. J. WHITMEE ON PALOLA VIRIDIS. 499 the Palolo on the morning of the 12th, when the moon quartered. In this I was not disappointed. They were more abundant this year than they had been the previous one. I confined my attention almost entirely to the contact of the worms with each other, and to their breaking into pieces. Early in the morning I caught three green and three brown ones, and placed them in a large glass vessel which I had provided for the purpose. While observing the worms which were swimming freely in the sea, I also kept m y eye upon my captives. I saw no sexual contact either between those in the vessel or those in the sea. They all went gyrating about until a little after sunrise. Then I observed those in the vessel begin to break, first into long pieces, each example separating into two or three parts, while these pieces continued to subdivide into minute portions. I observed those in the sea divided in the same manner and at the same time. This continued till about 8 o'clock A.M., by which time those in the sea had nearly disappeared. The six worms in the vessel were also completely broken up, the water (about half a gallon) being rendered somewhat turbid, as if a dessert-spoonful of milk had been mixed with it. The green ova were floating in all parts of the water, but were gently settling towards the bottom. The empty cysts of the defunct worms were lying on the bottom of the vessel. I brought them home with me, and emptied the whole into a small aquarium, which I am leaving undisturbed to see if the eggs will develop there*. By the time I reached home, about 1 P.M., all the ova had settled to the bottom of the vessel, notwithstanding the constant agitation of the water by th* motion of the boat in which I brought it. I wish specially to direct attention to the following interesting fact respecting the appearance of the Palolo. Although it comes only at one particular state of the moon (the time of the last quarter), it still keeps solar time in the long run. As far as I have certain information, it has only been seen in October, November, and occasionally, but very rarely, in December. Now it is evident that if the intervals between its appearance were regularly 12 lunations, the months during which it is found would be constantly changing, since it would appear about 11 days earlier each year. If, on the other hand, the intervals were regularly 13 lunations, it would come about 18 days later every year, and tlie months of its appearance would change still more rapidly. Having only lately given any attention to this matter, it was with considerable surprise I discovered, from the dates of its appearance, that in each period of three years there are two intervals of 12 lunations each, while in one interval there are 13 lunations. Unfortunately the observations given in the early part of this paper were not all consecutive, so that I cannot say positively that the length of the intervals proceeds in regular order, two years ot 12 lunations being invariably followed by one of 13 lunations ; but the rule holds good in the aggregate of 12 years over which the observations extend, there being 8 years of 12 lunations each, and 4 years of 13 lunations each. This will appear from the following Jable, in * P.S. They did not develop in the aquarium.-March 17, 1875. |