DEPARTMENT OF MARINE BIOLOGY.* 



Alfred G. Mayor, Director. 



In December 1918 the students of the United States Officers' Naval 

 Training Unit at Princeton University were discharged, thus relieving 

 the Director from his duties as instructor in navigation to the school 

 for ensigns in the Naval Reserve. 



Also, on January 2, 1919, the Navy Department returned the yacht 

 Anton Dohrn, which had served as a patrol vessel guarding Key West 

 harbor, being designated as S. P. No. 1866 in naval records. She had 

 been leased to the United States Navy since July 31, 1917, for $1 per 

 annum. 



Accompanied by Dr. Paul Bartsch, the Director went with the Anton 

 Dohrn to inspect the Tortugas Laboratory, which we had been unable 

 to visit since August 1917. Our chief object was to ascertain the con- 

 dition of the property and to form an estimate upon the cost of repairs 

 and expenses of upkeep. We also wished to provide Dr. Bartsch with 

 an opportunity to study the colonies of Bahama cerions which he had 

 established on the Florida Keys between the mouth of Key Biscayne 

 Bay and Tortugas in 1912, and which had given rise to a generation 

 derived from parents born in Florida. 



Dr. Bartsch found that on New Found Harbor Key the Bahama 

 cerions belonging to the Glans division of the genus had crossed with 

 the native Florida cerions, which belong to the Incanum division. The 

 first generation of hybrids show characters about intermediate be- 

 tween the two parent stocks, but the next generation born of these 

 hybrids exhibit an extraordinary variety in form and color-pattern, 

 giving rise to many individuals quite unlike any cerions hitherto known, 

 and so distinct that they may prove, should they breed true, to be new 

 species derived from a new equilibrium of chromosome elements due to 

 recombinations resulting from the cross. The matter may throw 

 light upon the manner of origin of the numerous localized races of 

 Achitenella in Oahu or of Partula in the valleys of Tahiti. 



In order to test its biological significance, Dr. Bartsch again visited 

 Tortugas in May, and 105 wire cages were made by Mr. John Mills 

 and placed out upon the meadow in the center of the island in order to 

 enable him to isolate selected pairs of these snails in an attempt to study 

 the inheritance of characters in their offspring. These cages were, how- 

 ever, destroyed by the hurricane of September 10, 1919, and it will 

 be necessary to start the experiment again as soon as possible. 

 .fe Also, at Tortugas we took up the corals which had been planted out 

 upon the reefs in July 1917, and these showed that when, on account of 

 old age, a coral has ceased to grow or is growing slowly, isolating 



*Situated at Tortugas, Florida. 



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