Of the different oils investigated, fresh lubricating oil mixed 

 vdth carbonized sand was not toxio to Tubularia or toadfish embryos. 

 It seems apparent that this oil liberates little toxio material to 

 tile sea water as compared with crude dil, Diesel oil, or Navy Grade 

 Special fuel oil. It is possible that waste crankoase oil, which 

 may enter our waters as a pollutant, may contain added materials that 

 may be highly toxic but this material was not tested in the present 

 experiments* 



In the experiments with toadfish embryos it was found that the 

 toxicity of crude oil and carbonized sand mixture varies with the 

 amount of oil used* As can be seen from figure 2, the plot of log 

 y (concentration) against log x (time of survival) approximates a 

 Ttraight line, indicating that^ttie relationship laay be expressed by 

 a simple equation of the general type y^ a3c°, 



Alt^hough weaker concentrations of oils, oil extracts, and small 

 quantities of mixtures of carbonized sand and oil may not result in 

 an immediate lethal effect, they exert a deleterious action which may 

 eventually bidng about death of the organisms* An altered physiology 

 of oysters was observed when these substances were added to the water* 

 There was a disruption in the aotlon of the water-pumping raeoheoiisms of 

 the gills, which In all lamelllbranoh mollusks serve to bring freshwater 

 for respiration and feeding* In addition, the presence of oils caused 

 the oysters to remain closed within their shell for longer periods, 

 greatly lessening the time a'vailable for feeding* 



Nelson's experiments with the effect of oil on adult oysters show 

 a damaging aotlon, agreeing in many respects to the findings of the 

 present experiments* He summarizes his tests as follows (Nelson, 1925, 

 page 179) I "Regarding the effects of oil upon adult oysters let me 

 cite experiments which I performed in 1920 in preparation for testimony 

 in the case against an oil company at Providence, R. I*, in May, 1921. 

 The oysters were kept in two tanks of bay water of known purity; one 

 tank served as control, the other was kept covered by a film of oil* 

 llw waste in both tanks was frequently agitated to simulate wave action, 

 and at no time did tiie oxygen saturation fall below 80 per cent. (It has 

 been shown that oysters do not suffer until the saturation falls below 

 30 per cent.) After 15 days the oysters from the two teuiks were opened 

 and compared* Those fr<an the oil-covered tank showed marked contraction 

 of the mantle, the blood vessels revealed many bluish nodules character- 

 istic of oysters living under unfavorable conditions, and the bodies of 

 tiie oysters were distinctly thinner and poorer' than those of the controls* 

 Preserved samples of each lot show the difference clearly even now*" 

 The experiments indicate a disturbance in the rate of water filtration 

 and feeding, such as was found in the tests performed in the present 

 paper* 



45 



