374 U. S. BUREAU OF FISHERIES 



Observations on the spawning; of oysters made by P. S. Galtsoff 

 and J. F. Reppiin at Woods Hole disclosed some interesting details 

 of this process. It has been found that the eir<i;s of an ovulating 

 female pass through the gills and are discharged from the inhalent 

 chamber instead of being expelled directly with the outgoing current 

 of water jDassing through the cloaca. Because of this ])eculiar man- 

 ner of shedding, the eggs are more uniformly distributed in the water 

 and have a better chance to meet with the sperm. Experiments with 

 artificial stimulation of spawning produced interesting results, show- 

 ing that male oysters can be induced to shed sperm by a great variety 

 of organic compounds, as, for instance, various hormones (thyrosin, 

 theelin, two extracts of pituitary gland), sugars. pe])tone, e^x^^jc albu- 

 men, sperm of various mollusks, and even yeast. The reaction of 

 the female is, however, very specific; it can be induced only by the 

 sperm of the oyster. 



OIL-POLLUTION INVESTIGATIONS IX LOUISIANA 



In an attempt to carry out a more comprehensive study of the oil- 

 pollution problem in Louisiana, wdiere a serious mortality of oysters 

 occurred in 1932-33 coincident with the development of oil wells, 

 the Bureau obtained from the Civil Works Administration an ap- 

 proval of a project to carry out both field and laboratory experiments 

 in the affected territory. Unfortunately, out of the $42,000 allotted 

 for this purpose only $3,000 were nuide available to the Bureau, and 

 after the completion of a preliminary hydrographic survey of 

 Timbalier and Terrebone Bays and adjacent bodies of water by 

 R. O. Smith, the work in Louisiana was discontinued. Laboratory 

 experiments were carried out, however, by H. F. Prytliercli and R. O.. 

 Smith at Beaufort, N. C, and P. S. Galtsotf and V. Koehring at 

 Woods Hole and Washington. Although the exact cause of the 

 mortality of oysters had not been determined, the results of the 

 laboratory experiments throw light on the ])Ossible effect of oil 

 pollution on oysters. The report of this work has been submitted 

 for publication. 



The laboratory experiments were designed to test the effect of crude 

 oil and oil-well bleed w^ater on the vital activities of the oyster, espe- 

 cially on the rate of feeding, and on the growth of diatoms which 

 constitute the principal food of the oyster. Using a method devel- 

 oped by Galtsoff in his previous studies on the physiology of feeding, 

 hundreds of records Avere obtained showing the effect of the presence 

 of oil on the rate of pumping of water through the gills. The I'esults 

 of these observations show tliat crude oil contains certain soluble m 

 the sea water substances which inhibit the activity of the ciliated 

 epithelium of the gills and reduce the amount of water which the 

 oyster passes through the gills. This toxic effect is j^roportional to 

 the concentration of the water soluble fraction of crude oil. It is of 

 interest that repeated washing of one sample of oil seems to have no 

 effect on toxicity of the extract, for samples of it obtained from oil 

 that had been washed 28 times Avere as toxic as those prepared from a 

 new sample. Oil extracts have no effect on tlie adductor muscle and 

 oystei's kept under oil or in running sea water Avhich was allowed to 

 pass through a layer of oil remain o])en for the same periods of time 



