The Life History of Tillina Magna 409 



Calkins and Lieb ('03) found that alcohol prevented to some 

 extent the fall into periods of depression, and prevented the extinc- 

 tion of the lines. Woodruff ('08) finds that alcohol may have oppo- 

 site effects, causing an increase in the division rate at one time, 

 and a decrease at another time. He also states that when an 

 increase in the division rate takes place, this effect is not lasting, 

 but is soon followed by a period of low vitality, even below normal. 

 All experiments treating Tillina with alcohol solutions of different 

 strengths proved fruitless. In every case the division rate was 

 lowered, the vitality weakened, and the lines thus treated died 

 out in a short time. 



In the 20th period, a second series of K2HPO4 experiments was 

 started, the individuals being taken from the main culture, as 

 was the first set, and treated in the same way. This culture proved 

 to be the most successful of all, and was the one to live through 

 the very serious depression period of July, and also furnished the 

 last individual to die on December 15, 1907. As Diagram III 

 shows, at the beginning of the 23d period, this culture was divided, 

 B9 and Bio being left untouched, while Bi i and B12 were treated 

 with a second stimulation. As a result of this treatment, the 

 re-stimulated lines lived, while the B9 and Bio lines died. 



At the beginning of the 25th period, on July 5, there was a 

 marked decrease in the division rate of all the lines, and the control 

 culture died on July 14. The beef culture was treated again, but 

 succumbed at the same time. An extract of calf 's brain was given, 

 but this had no effect. Alcohol also, was found to have no influ- 

 ence. Finally the numbers of stock material and individuals in 

 the K2HPO4 culture were reduced to nine, all of which survived 

 this period of extreme exhaustion. This culture, four lines of 

 which became the main culture, was stimulated again on July 

 II, and again on August 5. At the beginning of the 31st period, 

 the main culture was left untouched, and a new culture of four 

 lines from the stock of B12 was re-stimulated. The diagram 

 shows that the main culture died at the end of the 34th period, 

 while the new culture, which was again stimulated in the 32d 

 period, increased in vitality, the division rate averaged 1.26 divi- 

 sions per day, the highest point reached during the life history. 



