1892.] NATURAL SCIENCES OF PHILADELPHIA. 351 



doing, even reestablishing the insertion of the 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 regenera- 

 tion of the lost right valve. The pigment developed during expos- 

 ure to light in the mantle and gills in oysters with the riglit 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 pig- 

 mented because it is the only portion of the animal which is 

 normally and constantly subjected to the stimulus of light. 



Oysters which had the right valve removed were found to live 

 13erfectly well in the marine aquaria at Sea Isle, and would no 

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

 tinue his experiments there. The most remarkable results obtained 

 as a consequence of these experiments were that the adductor 

 muscle was soon attacked by bacteria and destroyed by putrefac- 

 tion while the great ganglion underlying it remained uninjured. 

 The pericardiac 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 con- 

 sequence 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 investi- 

 gation upon other univalve and bivalve mollusca, viz : experi- 

 mental researches as to the eflect of removing the valves and 

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

 freshwater, might obviously be experimented upon with very in- 

 structive results as respects the questions raised by the present 

 communication. 



The hermaphroditism and viviparity of the oysters of the Nor 

 ivest coast of the United States.— Fuof. J. A. Ryder also reported 



ih- 

 on 



