278 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1936 



at the Zoological Park. Dr. Clark, however, could spare none of 

 his specimens. All were needed to demonstrate the susceptibility 

 of the vampire itself after biting infected cattle or being injected 

 with the organisms. It was there indicated, and since proved, by 

 Clark and Dunn, that after biting infected cattle, the bat continues 

 its blood feasts night after night, but itself succumbs in a period of 

 about 30 days. 



The senior author decided to return to Panama the following 

 summer and search the caves where vampires had been captured. 

 Hence in August of 1933, accompanied by Arthur M. Greenhall, 

 then a student at the University of Michigan, Panama was again 

 visited and Dr. Clark provided guides to explore the Chilibrillo 

 Caves in the Chagres Valley. We were informed that the caves were 

 of limestone formation, with horizontal tunnels. In some parts 

 these gave way to large chambers, from which again other tunnels 

 led into the mountain. We w^ere equipped with headband lamps 

 and batteries carried on our belts. 



In a shack near the caves was an illustration of the frequency 

 with which humans may be bitten by vampire bats. A boy about 10 

 years old had been bitten five times during a week, and always on the 

 under surface of his toes while he slept. He had bled profusel}', 

 and the earthen floor beneath his slatted bed was blood-stained each 

 morning. 



The route to the caves led through cattle trails in low, green 

 tangle, with ankle-deep mud most of the way, as the period was the 

 rainy season. There was a steep slope near the caves and a growth 

 of rain-forest. The Panaman guides, pushing through barricades of 

 vines, disclosed a hole in the ground. It appeared to be little more 

 than the entrance to a coal chute. We slid in and found ourselves in 

 a horizontal tunnel in which we could walk upright in single file. 

 The tunnel soon grew wider and higher, the floor slippery with red 

 mud. Through portions of this entering gallery there was swiftly 

 flowing water, knee deep in places. It appeared to come through the 

 sides, then to seep through crevices in the floor. By pointing a light 

 overhead, a double procession of big bats could be seen, the two 

 streams flying in opposite directions. 



After we had worked forward a fair fraction of a mile, the sub- 

 terranean stream gave way again to the slipj^ery floor. The hallway 

 became larger and now showed side galleries. The guides stopped 

 there to assemble the handles of the nets by which the bats were to be 

 taken. The atmosphere was unlike that of caves in the temperate 

 latitudes; the air was hot, heavy, and sweetish, the latter condition 

 resulting from the odor of thousands of bats. Common on the lime- 

 stone walls were huge roaches, of pale, straw color. Another insect 



