THE OXYGEN REQUIREMENTS OF SHELLFISH. 
By PHILIP H. MITCHELL. 
The respiratory exchanges in lamellibranchs seem not to have been investigated. 
Probably the most notable work related to it is that of Vernon.® He measured the oxy- 
gen utilization and carbon dioxide emission in a large number of marine forms, including 
certain Mollusca but no lamellibranchs. He showed that in the lower marine forms 
investigated, including Coelenterata, Tunicata, and Mollusca, the respiratory exchange 
was very small compared to the higher ones, for example, teleosts. There were, however, 
certain exceptions to this rule, notably the protozoan Collozoum inerme, which showed 
nearly as high a respiratory exchange as the fishes. He found also that, in general, the 
respiratory activity was more readily responsive to temperature in the lower than in 
the higher forms. He further showed that the gaseous exchange was relatively greater 
in the small than in the large individuals of the same species and found that, in general, 
the same distinction held between small and large species. The transparent pelagic 
animals were shown to have a very small proportion of solid organic matter in their 
tissues, so that calculated on that basis their respiratory activity was very large, greater 
indeed than fishes, amphibians, or even mammals. 
In the present work some of those findings have been confirmed for the lamelli- 
branchs. They show a ready responsiveness to temperature changes, a smaller utili- 
zation of oxygen in proportion to the body weight with increase in size, and those forms 
which showed a low oxygen requirement in relation to their entire weight showed a 
higher utilization in proportion to their dried weight. 
The resistance to lack of oxygen in forms which have no power of locomotion is 
an important factor in adverse conditions. This is especially true of the edible shellfish, 
which, because of enforced closure during cold weather, or in the presence of polluted 
or roily water, or in water whose oxygen has been lowered by the presence of certain 
wastes or an abundance of life, must at times be deprived of their normal supply of 
oxygen. The subject therefore possesses an economic significance, and it was, in fact, 
the possibility that certain manufacturing wastes, removing oxygen from sea water, 
might therefore cause the death of oysters and clams which first directed the writer’s 
attention to the subject. The particular wastes involved were those of gas works con- 
o- Vernon, H. M.: Respiration in marine forms. Journal of Physiology, vol. xix, 1895, p. 18. 
