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[in Japanese]

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Forty mongrel dogs, fifty rabbits, sixty guinea pigs, one hundred and fifty rats, fifty hamsters, and eight frogs were used for the experiments of determining their acceleration tolerance limits.
Centrifugal acceleration was given to the animals in three ways, headward direction (+Gz), tail warddirection (-Gz), and forward or backward direction (Gx) . Given magnitudes of acceleration were +10 Gz to dogs, +15 Gz, -5 Gz and 15 Gx to rabbits, guinea pigs and rats, and +15 Gz and -15 Gz to frogs. Full lethal time, half survival time, and full survival limit time for the acceleration loads stated above were determined in all species of animals and the result is as follows.
1) Dogs which were given +10 Gz of acceleration, showed 100% lethal time of 8 to 11 minutes, half survival time of 3 to 5 minutes and full survival limit time within one minute.
2) In rabbits which were given +15Gz of acceleration, 100% lethal time was 7 to 9 minutes, half survival time was 5 to 6 minutes, and full survival limit time was within 2 minutes. In case of -5 Gz of acceleration all rabbits killed in 10 to 13 minutes, half survived in 5 to 7 minutes and all survived within 2 minutes. Gx was more tolerable ; i. e. rabbits showed 100% lethal time of 13 to 15 minutes, half survival time of 8 to 11 minutes and full survival limit time within 6 minutes for 15 Gx of acceleration.
3) Guinea pigs showed 100% lethal time of 17 to 20 minutes, half survival time of 13 to 15 minutes, and safe limit within 2 minutes for +15Gz. These tolerance times were 20 to 23 minutes, 5-8 minutes, and 3 minutes, respectively, in case of -5 Gz and 21 to 25 minutes, 9 to 11 minutes, and 6 minutes, respectively, in case of 15 Gx.
4) Rats showed 100% lethal time of 14 to 18 minutes, half survival time of 9 to 11 minutes, and safe limit within 30 seconds for +15Gz. These tolerance times were 15 to 20 minutes, 1-3 minutes, and 30 seconds, respectively, for -5 Gz and 21 to 25 minutes, 13 to 15 minutes, and 5.5 to 6.5 minutes for 15 Gx.
5) Hamsters which were given +15Gz, -10Gz and 15 Gx showed very longer tolerance times than those of rabbits, guinea pigs and rats.
6) Frogs showed the strongest tolerance to G as compard with mammals. All frogs were safely survived for more than one hour in case of +15 Gz and -15Gz.

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Mongrel dogs, rabbits, wistar strain rats, guinea pigs, hamsters, and frogs were given centrifugal acceleration load in three directional mode, i. e. +Gz, -Gz, and Gx, and heart rate was recorded before and during the stress. Changes of heart rate by G stress were compared with each species of animals.
In case of +Gz stress, rats and hamsters showed generally no change or slight slowing of heart rate during increasing G, but some animals showed abrupt bradycardia and ended to death. Hamsters had a tendency of recovering from abrupt severe bradycardia.Dogs, rabbits and guinea pigs showed a tendency of slight tachycardia during increasing G, and showed gradual successive slowing followed by death by continuring G stress.
Frogs had a strong tolerance and maintained normal heart rate all along the G stress.
In case of Gx stress, rats, hamsters and guinea pigs showed a tendency of slight slowing or remaining on the constant level, but some animals which were not able to tolerate to stress showed the same course as in case of +Gz stress.
Rabbits showed slowing from the start of G stress, sometimes transient increase, and marked bradycardia followed by death.
In case of -Gz stress, rats, rabbits, and guinea pigs showed successive bradycardia from the start of G stress and finally ended to death. But a few survived animals showed gradual recovery from marked slowing to normal rhythm. Hamsters showed a tendency of slight initial increase of heart rate, later abrupt bradycardia during constant G stress and ended to death.
Above stated results indicate that there are some variation of heart rate pattern during G stress by the directions of G stress and among the species of animals. In general, it may also say that the large animals such as dogs and rabbits have lower tolerance to G than small animals in view of heart rate change as many authors indicated the same results from many other indicaters.

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[in Japanese]

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