The food value of sea mussels / by Irving A. Field.

  • Field, Irving Angell, 1870-1921.
Date:
1911
Catalogue details

Licence: In copyright

Credit: The food value of sea mussels / by Irving A. Field. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

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    increased. After from twenty-four to thirty-six hours all the ripe mussels of a given lot were spawned out. It was observed that spawning started soonest among specimens which had been roughly handled before being placed in the trough. The duration of spawning varied with different individuals. Some would deposit practically all their products at one time, which required from twenty minutes to an hour. Others would spawn intermittently for short periods of several minutes each and finally stop altogether without having discharged half their genital products. A male mussel discharges a stream of milt which will color the water for a distance of ioor 12 feet before becoming too diffuse to be seen. In quiet water a female mussel will discharge her eggs so that they will fall in a heap. They can easily be removed by means of a pipette and measured in a graduate, a method which revealed the fact that mussels lay from i to 4 cubic centimeters of eggs at a single spawning. Knowing the average diameter of the eggs to be 0.07 mm., it is easy to calculate the number in a cubic centimeter, which approximates more than 3,000,000. On August 2, 1909, a mussel inches long was seen to begin the deposition of eggs. A homeopathic vial of about 10 c. c. capacity was immediately placed in such a position as to receive the string of spawn as it was discharged. The egg laying proceeded at a remarkably rapid rate and continued for 15 minutes, when it suddenly stopped. The mussel was watched for an hour longer and, when it was seen that no more eggs were to be laid, was removed from the trough and the shells opened to expose the mantle. The condition found is shown in figure 4 of plate xix. All of the eggs except little patches here and there near the edge of the mantle had been discharged. Of course it was not known whether any of the eggs had been laid before this individual had come under my observation. The number of eggs laid measured 4 c. c., which means that this mussel liberated in round numbers about 12,000,000 eggs in 15 minutes. This is possibly more than the number usually produced. Three other mussels under my observation liberated from 6,000,000 to 9,000,000 each. The period of reproduction varies for different regions and is influenced considerably by climatic conditions. It has been hard to determine when the mussel breeds on our northern Atlantic coast. Verrill and Smith (1873) and Goode (1887) say that the mussel breeds early in the spring. Ganong (1889), writing in Acadia, states that the height of the breeding season appears to be April and May. Mr. Charles H. Silverwood, of Pawtucket, R. I., who for years has been watching the habits of the mussels in Narragansett Bay, writes that the breeding season varies with the weather, beginning sometimes as early as the middle of June and lasting until late in August. Mr. George A. Carman, of Canarsie, N. Y., observes that the mussels in Long .Island Sound spawn during April and May, while those in the open ocean do not spawn until about Sep- tember 1. My own observations on the development of the sexual organs in mussels from Woods Hole, Mass., are in harmony with Silverwood’s statement. Specimens of mussels were collected every month from February 7 until August 24. The mantles were sectioned and mounted for microscopical examination. The series of preparations show a gradual development of the sex cells during the whole period. No mature