60 



University of California Piiblicatioiis in Zoology LVoi,. 16 



of serum about every forty-eight hours if the temperature is around 

 60° Fahrenheit. Allowing tissue to remain one day longer in same 

 medium, however, showed no decided retrogression of activity, although 

 it could be noticed. The following table shows the complete life- 

 history in serum of above discu.s.sed tissue. The tissue was prepared 

 in forenoon of February 17; the first noticed heart action was on 

 February 21 at 4:30 p.m. 



Comment 

 Evidently slowing down. 

 Less tissue active. 

 Small amount of tissue active. 

 's solution ; transferred to new drop 



Increasing amount of tissue 

 active. 



Increase with afternoon tempera- 

 ture. 



Slightly less tissue active. 

 Increase with afternoon tempera- 

 ture. 



Very much less tissue active. 

 Increase with afternoon tempera- 

 ture. 

 Only small part tissue active. 



Just outer tip active. Very weak. 



The tissue was washed in Ringer's .solution for fifteen minutes but 

 the heart action failed to revive, although outgrowths resulted later. 

 The tissue was purposely allowed to dwindle in activity (and amount of 

 tissue active) to see how great the revival would be. but it was left 

 a trifle too long. To avoid possible error in counting the beats, three- 

 minute records were always taken, counting the first fraction of a 

 beat as one and not the last fraction, and then dividing by three. • 



Often individual cells separated from the rest of the ti.ssues would 

 occasionally send out small strands of protoplasm, but the activity 



