Two decigrams of caffein can not be considered, therefore, the fatal dose for rabbits. This is further corroborated by the results obtained in experiments with larger doses. Rabbit 78, which received 257 mg per kilo, failed to show any symptoms. The same amount in proportion to body weight in No. 323 caused mild symptoms only, while the rapid death of rabbit No. 317 after the same dose of caffein may be explained by the lesion found at autopsy, thus affording additional evidence that disease may decrease the resistance to caffein. It will be observed that all the members of this series were young rabbits and, as will be shown later, young animals of other species are likewise more resistant to caffein than adult animals. Similar results were obtained by von Anrep, who observed that atropin is less toxic in young than in full-grown animals. Observations were also made on the diuretic effect of caffein when injected into the peritoneal cavity. The results shown in the following table indicates the stimulating effect on renal secretion whether the diet consisted of oats or of carrots. The urine of some rabbits contained moderate amounts of sugar after from 0.2 to 0.15 gram of caffein per kilo was given; albumen was observed in one case, but in none of the others. In rabbit No. 311 albumin was found before the injection of caffein, but none in the urine which was collected three hours after caffein was injected. _Effect of caffein on renal secretion._ -----+--------+---------+-------+--------------------+--------- No. | Weight.| Caffein | Urine.| Time. | Diet. | |per kilo.| | | -----+--------+---------+-------+--------------------+--------- |_Grams._| _Gram._ | _cc._ | | 307 | 1,320 | 0.150 | 100 | 4.5 hours | Oats. 308 | 1,305 | .150 | 180 | do. | Do. 295 | 1,205 | .100 | 100 | 2 hours 20 minutes | Carrots. 293 | 1,605 | .100 | 90 | 3 hours | Do. 292 | 1,595 | .100 | 105 | 4 hours | Do. -----+--------+---------+-------+--------------------+--------- NOTE.--The amount of urine secreted in three hours by control rabbits, on a carrot diet, varied between 35 and 50 cc, the average weight of the animals being a little above 1,600 grams. The secretion of urine on an oat diet was much less for an equal period of time. TABLE 3.--_Intraperitoneal injections._ SERIES A.