RESEARCH SEMINAR OF THE MARINE BIOLOGI- 

 CAL LABORATORY FOR THE YEAR 1903. 



The Research Seminar, begun in 1903, was devoted chiefly to 

 informal reports and discussion of work carried on at the Labora- 

 tory. It found abundant support and was continued for some 

 weeks after the regular courses ended. 



The range of subjects reported upon contrasts strikingly with 

 that of earlier years, when embryology was the main field of 

 productive research at the Laboratory. 



The following is a list of the subjects presented, with brief sum- 

 maries : 



July ij. The Anatomy and Embryology of Pecten tenuicost- 

 atus. By GILMAN A. DREW. 



Drawings illustrating the structure and development of this 

 form were exhibited and points of interest were discussed. Much 

 of the discussion concerned the nervous system, the circulatory 

 system, the formation of organs, and the excessive development 

 of the posterior portion of this animal. 



The visceral ganglia, which supply nerves to the greater part 

 of the body, are very complex, and the different structural regions 

 are very well marked. The pallial nerves have taken on gang- 

 lionic structure probably because of the man}' tentacles and eyes 

 on the mantle margin that they supply. The cerebral and pedal 

 ganglia are small, corresponding to the reduced condition of the 

 anterior portion of the body. Octocystic canals opening on the 

 surface of the body are present. 



The circulatory system comprises a definite system of blood 

 channels, but they are probably not lined with endothelium, so 

 that there is no sharp distinction between blood and lymph. 



July 75. The Origin and Relationships of the Rock Pigeons 

 as Revealed in their Color-Patterns. By C. O. WHITMAN. 

 The wild rock pigeons present two very distinct color-patterns 

 - (i) the chequered type, and (2) the barred type. 



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