March 31, 1899.] 



SCIENCE, 



479 



in sections, an example of whicli is shown 

 in Figure 1. Figui-e 2 shows free sperm 

 and sperm masses as they appeared in the 



Fig. 2. 



field of the microscope. Several oysters, 

 evidently males, were opened with the same 

 results. It yet remained to find living ova 

 in specimens containing spermatozoa in 

 order to more fully support my conclusions 

 as regards the bisexual conditions of this 

 species. This was not difficult, for I shortly 

 discovered in a specimen several immature 

 eggs floating amongst spermatozoa and 

 sperm masses. None of these ova were be- 



ing attacked by the male cells. Later, in a 

 specimen full of spermatozoa, I found a ma- 

 ture egg, completely surrounded by male 

 cells, which were attacking it with great 

 vehemence. Figure 3 (cam. luc.O^. 1, Obj. 



V; ) shows this egg, the light area evidently 

 denoting the position of the germinal ves- 

 icle. 



In the drawing only a portion of the pe- 

 riphery is represented as being attacked. 

 We know that in Ostrea Virginica the egg 

 does not become round until fertilized. Ar- 

 guing from analogy the egg shown above 

 has been fertilized. 



From the results of the work described 

 above I have no hesitation in declaring that 

 Ostrea lurida, the native oyster of the North- 

 west coast, is hermaphroditic. 



In this connection it is interesting to note 

 that Karl Mobius, in 1871, claimed that the 

 sexes of the European oyster, 0. edulis, are 

 separate at the breeding season {vide his 

 ' Untersuchungen liber die Fortpflanzungs- 

 verhaltnisse der Schleswigschen Austern.' 

 In 1877 (' Die Austern und die Austern- 

 wirtschaft') he concluded that the sex of the 

 European oyster changes after the repro- 

 ductive elements have been discharged from 

 the body. He has hardly valid reasons for 

 this conclusion. Professor John McCrady 

 (' Observations on the Food and Eepro- 

 ductive Organs of Ostrea Virginiana, with 

 some account of Bucephalus cucidus ;' Proc. 

 Boston Soc. of Nat. Hist., Dec. 3, 1873) 

 declares that he saw in 0. Virginica, among 

 small immature ovarian eggs, spermatozoa, 

 separate and in masses, moving about with- 

 out attacking the eggs and without any ap- 

 parent change taking place in the young 

 germinal vesicle. * 



F. L. Washburn. 



Biological Laboratory, 



University of Oregon, November 16, 1898. 



*In connection with Professor Washburn's paper 

 it may be desirable to quote the following note, from 

 the Proceedings of the Academy of Natural Sciences 

 of Philadelphia (1892, p. 351), to which Prof essor Conk- 

 lin has called our attention. " The Hermaphroditism 

 and viriparily of the Oi/sters of the Northwest Coast of 

 the United Slates. Professor J. A. Eyder reported on 

 behalf of Professor R. C. Schiedt of Franklin and 

 Marshall College, Lancaster, Pa., the latter's discov- 



