account for on any other theory than the one suggested. Were it not for the fact that controls, that is, animals of the same lot which had not received caffein survived all of the experimental animals, changed conditions of environment or accident might be considered the cause of death in the guinea pigs of the last series. TABLE 6.--_Subcutaneous injection of guinea pigs._ SERIES A. ------+--------+-------+----------+----------+--------+------+-------- Number| |Caffein|Appearance| Duration | | | of pig|Weight. | per | of | of | Diet. |Month.|Remarks. | | kilo. | symptoms.| life | | | ------+--------+-------+----------+----------+--------+------+-------- |_Grams._|_Gram._| | | | | 18 | 500 | 0.300 |2 minutes |2 hours |Carrots |March |Female. | | | |40 minutes| | | 15 | 548 | .290 | |30 minutes| Oats | do. | Do. 14 | 442 | 360 |15 minutes| do. | do. | do. | Do. ------+--------+-------+----------+----------+--------+------+-------- SERIES B. ------+--------+-------+----------+----------+--------+------+-------- 20 | 497 | 0.200 |2 hours |3 hours | Oats |April |Female. | | |20 minutes|30 minutes| | | 38 | 570 | .210 |25 minutes|2 hours | Carrots|Febru |Male. | | | |15 minutes| | -ary | 37 | 820 | .200 |1 hour |Less than |Carrots | do. | Do. | | |25 minutes| 18 hours |and oats| | 13 | 618 | .194 |25 hours | |Oats |March |Female. 36 | 850 | .200 | 1 hour |18 hours |Carrots |Febru |Male. | | |30 minutes| |and oats| -ary | ------+--------+-------+----------+----------+--------+------+-------- SERIES C.