2G2 Miscellaneous. 



diminutive pedal muscle upon the inner face of the imperfectly 

 reproduced right valve, which was deformed owing to the lack of 

 support of the right mantle, because of the removal of the original 

 right valve. As a consequence the right mantle was rolled up at the 

 edge, and this deformation of the mantle was reflected in the 

 attempted regeneration of the lost right valve. The pigment 

 developed during exposure to light in the mantle and gills in oysters 

 with the right valve removed which were kept alive in the aquaria at 

 Sea Isle City by Prof. Schiedt was wholly confined to the epidermis 

 as it normally is at the mantle-border in the unmutilated animal in 

 nature. The inference to be drawn from these facts is that the 

 development of pigment in the mantle and gills was wholly and 

 directly due to the abnormal and general stimulus of light over the 

 exposed surface of the mantle and gills, due to removal of the right 

 valve, and that the mantle-border, the only pigmented portion of the 

 animal, is pigmented because it is the only portion of the animal 

 which is normally and constantly subjected to the stimulus of light. 



Oysters Avhich had the right valve removed were found to live 

 perfectly well in the marine aquaria at Sea Isle, and would no 

 doubt have survived till now had Prof. Schiedt been able to continue 

 his experiments there. The most remarkable results obtained as a 

 consequejice of these experiments were that the adductor muscle 

 was soon attacked by bacteria and destroyed b}^ putrefaction, while 

 the great ganglion underlying it remained uninjured. The peri- 

 cardiac cavity was also torn open, exposing the heart completely, in 

 some instances. In these cases the heart continued to beat and 

 propel the blood through the other organs of the body as if nothing 

 untoward had happened. The maximum rate of pulsation of the 

 heart noted was 52 per minute, which is much greater than the 

 rate hitherto reported. 



The anus was also retracted into a new and more anterior 

 position, owing to the loss of support which it had suffered in conse- 

 quence of the sloughing away of the adductor muscle. "Whether 

 the adductor muscle thus sloughed away would ultimately be repro- 

 duced was not determined, since the experiments were interrupted 

 before the animals had time to present evidence of such regeneration 

 of the lost muscles. 



These experiments open up a most suggestive line of investigation 

 upon other univalve and bivalve mollusca, viz. : experimental 

 researches as to the effect of removing the valves and exposing 

 them to the light. Many other species, both marine and fresh- 

 water, might obviously be experimented upon with very instruc- 

 tive results as respects the questions raised by the present 

 communication. — Proc. Acad. Nat. Sci. PhUad. Nov. 15, 1892. 



The Hermaphroditism and Viviparity of tlie Oysters of the 

 North-ivest coast of the United States. 



Prof. J. A. Ryder also reported on behalf of Prof. R. C. Schiedt, 

 of Franklin and Marshall College, Lancaster, Pa., the latter's 

 discovery of the fact that the oysters native to the north-west coast 



