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were taken, and this is without doubt caused by the difference of temperature. Professor Brooks 

 also states that there was a great deal of cold, rainy weather during June, and two hail storms. 

 The rainy weather would affect the density of the water by increasing the volumes of the various 

 creeks and rivers, and the changes of density would probably affect the production and emission 

 of the generative matter. It is an interesting coincidence at least, that the oysters found to be 

 fattening with the products of generation unexpelled were either from beds in comparatively shoal 

 water, or from the shoal parts of deep-water beds, and that those oysters should have been ripe 

 and spawning during the month of June. Again, it may be that the lowness of the temperature 

 prevented the deep-water oysters from ripening as soon as usual, and the mildness of the succeed- 

 ing autumn may have prevented the destruction of the ova and spermatozoa, thus rendering 

 possible the fertilization achieved by me in October, as the oysters from which I procured the ova 

 and spermatozoa were taken from deep water. 



Probably the influence of changes of environment, especially of density and temperature of 

 the water, is most severely felt by the embryo when in their free swimming state, and, in connec- 

 tion with the want of success of the spatting season in the Sounds, it is noticed that the tempera- 

 ture curves show a maximum change about the time when it is supposed that the young would 

 attach in largest numbers, or when they were swimming about in the water- It is also worthy of 

 notice that Professor Brooks, about this time, met with the minimum amount of success in his 

 efforts to artificially raise the embryo. 



In consideration of the foregoing, I am of the opinion that the success or failure of any spatting 

 season is dependent upon the equability of the temperature; that .the higher the temperature 

 during the spring months the earlier will be the advent of the spawning season, and that an 

 increased temperature will also hasten the development of the spat, and of the young oysters after 

 they have become attached. I also infer that sudden and extensive changes of density will like- 

 wise affect the advent, duration, and success of the spawning, though to a less extent. Subsequent 

 to the attachment of the animal, changes of the conditions surrounding it are not of so much 

 importance, though naturally such changes will more severely affect the delicate organism of the 

 young oyster than that of the older and more hardened adult. 



During the first six months of its existence the oyster is exposed to the greatest danger from 

 the numerous enemies which surround it. The thiu, delicate shells, from one-sixteenth of an inch 

 to one inch in diameter, are readily bored by the drills or torn off by the crabs, and the immense 

 number of both leaves no room to doubt their destructive effects. As an instance, the inspection 

 of the spat collectors in the Big Anneniessex River shows that during the early mouths of their 

 existence about 50 per cent, of the young oysters were destroyed. Naturally, as the animal pro- 

 gresses, it becomes more hardy and better able to resist the attacks of enemies and changes of 

 environment, and thus we find on the un worked beds, where the oysters are practically in a 

 natural state, that the decrease in passing from young growth to mature oysters is about 30 per 

 cent., or about one-third of a given number perish in passing from the first to the fourth year of 

 their existence. 



Here our information ceases, but enough has been gathered to indicate the ratio which nature 

 has assigned as necessary between the young and the mature oysters. For every 1,000 of the 

 latter there should be 1,500 of the former, if the number of brood oysters necessary to maintain the 

 fecundity of the beds is to be kept up, and though this ratio is based upon data which are not quite 

 sufficient, yet, as I have said, it is all that has been afforded as yet, and may be accepted within 

 certain limits. Certainly, whatever it should be, the number of the rising generation of the ani- 

 mals should never be less than that of the older, or there should always be as many young as 

 mature on any bed, and a greatly increased ratio of young to mature oysters would show either 

 one of two things — either the mortality in passing from youth to maturity was much greater than 

 shown by the dredging results in the bay, or that a very large number of mature oysters had been 

 removed by other than natural causes. 



In considering these several beds the question of food and other necessary supplies has not 

 been considered, as it is evident that where an oyster bed is formed and exists naturally, all the 

 conditions for its successful life are probably present, and any failure of an important supply would 

 be followed by a speedy extinction of all the oysters on the bed. Such determinations of the quality 



