8 TECHNICAL BULLETIN 2 3 8, U. S. DEPT. OF AGRICULTURE 
various workers {51, 85, 95, 102, 110, 134). Popenoe (121) suggested 
the use of thallium as an ant poison. 
PRODUCTION OF ALOPECIA (LOSS OF HAIR) 
Several investigations have been made to determine the nature of 
thallium action in the production of alopecia {8, 61, 70, 71, lJf5, 143) . 
In 1898, Hallopeau (83) rubbed a salve containing thallium acetate 
upon the back of a guinea pig; the pig died but the hair was un- 
affected. In 1900, Buschke (13) observed that the feeding of very- 
small quantities of thallium to rats produced alopecia, and had a 
cumulative action. In a subsequent report (14), he noted that thal- 
lium acetate or carbonate produced alopecia in mice, rats, and mon- 
keys; in rats it had a central action, since the diaphoretic action of 
pilocarpine was not altered. The series of papers by Buschke and 
coworkers clearly demonstrated that thallium action was exerted 
upon the sympathetic nervous system. The hairs of the scalp and 
chest, under the control of the autonomic nervous system, were 
loosened readily by thallium; the hairs of the eyebrows and lashes, 
and those upon the abdomen not under the control of the autonomic 
system were unaffected. One-tenth of a milligram of thallium 
acetate fed rats daily produced alopecia (39). Other workers also 
showed that the hairs upon the scalp and abdomen were most 
readily removed; lanugo and abdominal hairs with more difficulty; 
hairs at the nose and snout not affected. The local application of 
thallium did not cause loss of hair. A 5 per cent thallium acetate 
salve killed rats in four days; 20 per cent in two days; more rapid 
deaths were not produced {113, 139). 
Dixon {62) reported a very thorough study of the mechanism of 
depilation by thallium. He found that no other substance has a 
similar action in producing alopecia; that thallium has this action 
upon all animals with the possible exception of the guinea pig. The 
hair at first becomes less glossy, then is easily rubbed off after 
about seven days. After 14 days it is easily shed, practically all 
hair being out by the nineteenth day. Alopecia begins at the nape 
of the neck and around the ears; hairs from the chin and the nose 
are the last to be lost. The new growth of hair starts in about the 
fourth week, and is completed by the end of the second month. Local 
applications of thallium did not cause depilation or affect the blood 
vessels. Interruption of growth of the hair was due to failure of 
transition of the large polygonal cells to stratified cells of the hair. 
Very large doses caused degeneration of the hair follicles. Thallium 
w^as found to increase selectively the reactivity of the entire auto- 
nomic nervous system, just as strychnine increased the activity of 
the spinal cord. Thallium was excreted in the urine, but did not 
appear to injure the kidneys or to cause albuminuria. Spectro- 
scopically it was found in practically every tissue of the body. 
Truffi {14^) found that rats were more sensitive than guinea pigs, 
cats, or rabbits. Inunction gave circumscribed depilation, because 
of action on the hair follicles. 
ACTION OF THALLIUM SALTS ON MAN 
During his original work in 1863, Lamy {94) developed general 
lassitude and pains of the lower limbs, which he attributed to the 
