250 TREUBIA VOL. II, 2—4. 
When this embryo was perfectly quiet the heart beat 140 to 143 to 
the minute. On the slightest disturbance however the number of heart- 
beats instantly decreased. Thus I counted in a minute when a Copepod 
swam against the egg, 132 beats only, and in a minute when a door 
banged in the distance 138 beats. Also when the embryo turned about 
inside the egg-capsule the number of beats regularly declined to 139 a minute. 
This diminution of the number of pulsations was always due to the heart stop- 
ping, be it ever so short a while, upon the disturbances mentioned. By giving 
the table a hard push or by moving the eggs to and fro with a couple of 
needles, I could however cause the embryo’s heart to stop for as many as 
20 seconds. Subsequently the heart began to pulsate again, slowly at first 
and gradually more quickly, as may appear from the following two tables: 
FIRST EXPERIMENT. 
Consecutive number of Number of pulsa- 
| the heart-beat synchron- Number of tions per minute. 
Moment of Time | izing with the moment pulsations in (In the perfectly 
of time marked in 10 seconds. undisturbed 
the first column. embryo !40—143.) 
Diseconder een ne dec 
| 0 0 
10 Seconds | 0 | 
a | 1 6 
20 Seconds 1 
| 3 18 
307Seeonds | 4 
| 8 48 
40 Seconds | 12 | 
| | 9 54 
50 Seconds | 21 
| 12 72 
60 Seconds 33 
| 13 | 78 
70 Seconds | 46 | 
| | 17 | 102 
80 Seconds = | 63 | 
| | 20 | 120 
90 Seconds | 83 
| | 23 138 
100 Seconds 103 
21 126 
110 Seconds | 124 | 
| 22 182 
1202Secondsr | 146 
| 23 138 
(SO, Seconds iam 169 
| 24 144 
140 Seconds 193 | 
ETS 
