474 



THE AMERICAN NATURALIST 



[Vol. LYI 



the laboratory by twenty females over 100,000 larva? were reared. 

 On the eve of my departure from Woods Hole the larvae were 

 all carefully removed from their tubes and placed in half-gallon 

 Mason jars. Each jar contained 500 c.c. of the rich Beaufort 

 diatom culture and sea-water to within ten centimeters of the 

 top. The jars were then tightly covered and set aside. After 

 the worms had had time to build new tubes, the jars were shipped 

 to Washington, D. C. The worms at this time averaged about 10 

 mm. in length. Early in June, 1914, these worms were shipped 

 from Washington to Woods Hole. Relatively few survived the 

 journey. The largest worms (females), brought carefully in a 

 hand bag, died before the journey was half made. Since during 

 the W'inter hundreds of these worms had been killed periodically 

 for future study, the number left from the 1913 culture had been 

 greatly reduced. Some animals of this culture were carried 

 through the summer of 1914. They never reached sexual matu- 

 rity. They were taken back to Washington at the end of 1914. 

 In 1915 they were brought back to Woods Hole and returned to 

 Washington that fall. During this period they still showed no 

 change. 



In Washington the animals were kept in the clamped jars with- 

 out any change of water or additions of distilled water. One 

 culture was kept in a battery jar covered with a glass plate. Nor 

 was any addition ever made to this culture. The jars were kept 

 at room temperature in subdued light. To avoid contamination 

 worms removed for study were from the culture in the battery 

 jar only. After observing the worm I never replaced it, but 

 killed it for in toto mount or sectioning. 



In 1917 several very fine cultures of worms w^ere started, but 

 they died in transit to Washington. In 1918 and 1919 no worms 



The 1920 Culture.— In August, 1920, very beautiful cultures 

 of about 50,000 larva? were started : unfortunately, the majority 

 of these died very suddenly late in August. About a thousand 

 worms survived. These were distributed among twelve dishes 

 with food and left over winter in the heated laboratory at Woods 

 Hole. The dishes were left covered with glass plates exposed to 

 north light. No change was made in the water or any additional 

 food given during the period September 1, 1920, to June 1, 1921. 

 On May 17, 1921, about 200 worms of different sizes were found 

 in the dishes. Of these some were preserved from time to time. 



