178 CARNEGIE INSTITUTION OF WASHINGTON. 



muscular activity, the respiration appears to be directly proportional to the 

 mass of tissue, as was shown to be true of the Alcyonaria. 



In experiments where actively pulsating half-disks were compared with 

 halves of the same disks which were rendered inactive by the removal of their 

 sense-organs, the average oxygen consumption of all the active halves was 

 1.8192 c.c. O2 per hour; that of the inactive halves was 1.1367 c.c. O2 per hour. 

 When active halves were compared with their mates in the muscles of which 

 a circuit wave of contraction was maintained the oxygen consumption was 

 2.1034 c.c. for the active specimens and 2.041 c.c. for the activated specimens. 

 In these last-mentioned experiments several half-disks were frequently put 

 into each of the jars, so that no comparisons based upon these figures can be 

 drawn between the two sets of experiments. 



With the more accurate determinations by the Winkler method than was 

 possible with the colorimetric method of measuring the metabolism that was 

 used last year, it was found that in 4 of the 20 experiments the activated halves 

 were respiring more rapidly than their normally pulsating mates, and that in 

 5 experiments the respiration was the same for both sets of half-disks. In 

 these 9 experiments the activated half-disks were pulsating from 3.5 to 5 

 times as rapidly as those with sense-organs. When a labyrinth of 8 sections 

 was made in the tissues of the activated specimens, so that their pulsation-rate 

 was only from 1.2 to 1.7 times that of the halves under the control of the sense- 

 organs, the respiration of the former was 66 per cent that of the latter. 



When a number of series of half-disks of the two last-mentioned types 

 were kept for several days and the metabolism determined each day it was 

 found that the differences in the rate of metabolism became progressively 

 smaller and smaller, as was true of the differences in the rate of regeneration 

 or loss of weight during starvation, as determined in previous experiments. 



In all cases where it was carefully determined, the respiratory quotient varied 

 from 0.82 to 0.94. At first this value was not constant even for the same disk 

 from one experiment to another, showing that different sorts of materials were 

 being oxidized from time to time. In any long-continued experiments, how- 

 ever, the respiratory quotient reached a practically constant value after the 

 tissues of the bodj^, chiefly the mesogloea, were being consumed. This con- 

 stant value was lower than that obtained in experiments carried out on disks 

 shortly after they had been brought into the laboratory when some of the 

 natural food-material would still be present in the gastral canals. A similar 

 condition was recorded by Mayer and by Hatai in studying the loss of weight 

 during the starvation of Cassiopea, both of whom observed that the results 

 for the first day of starvation were unreliable on account of the differences 

 in the rate of starvation due to varying amounts of food in the gastral cavity. 



On the Condition of the Albino Rats on East Key and Garden Key in the 

 Dry Tortugas, by S. Hatai. 



In the season of 1916, Dr. Donaldson reported on an "Experiment on the 

 Feralization of the Albino Rat," 8 animals having been placed on East Key 

 in the summer of 1914. Six of these animals were recovered in 1916, but the 

 effect of the wild life on the relative weight of the nervous system could not 

 be studied on this material. 



In July 1916, 30 pairs of albinos were released on East Key, and 11 males and 

 13 females on Garden Key. All of these were about 100 days of age and were 

 ear-marked. During the present season (1917), I endeavored to determine 

 whether (1) these rats had lived through the year; (2) had been able to breed; 

 and (3) whether they showed any significant modifications in the relative 

 weights of the central nervous system or the ductless glands and the gonads. 



