22 BULLETIN 1391, U. S. DEPARTMENT OF AGRICULTURE 
These experiments show very clearly that the poison may be trans- I 
mitted to the offspring by the milk. They also show clearly that, I 
while it is possible that the offspring may be affected without the j 
mothers showing any symptoms, the poisonous substances are not in 
all cases, perhaps very seldom, excreted so completely as to prevent ] 
the exhibition of symptoms in the mothers. 
These results have an important bearing on the use of milk and I 
butter from herds affected by the alkali disease. The data at our j 
command seem to show that the belief held by many people that it is 
dangerous to use milk or butter from such animals is well founded. 
There have been cases of human sickness that, to all appearances, 
were caused by the use of milk or butter from sick animals or from j 
animals that were eating largely from the rayless goldenrod. It 
is difficult and perhaps impossible to get definite proof that cases of 
milk sickness in human beings have arisen in this way, because of 
the necessary limitation of experimental work on human beings. | 
The results, however, are sufficiently definite so that it is reasonable 
to caution people against using, to any large extent, milk or butter 
from cows which either show symptoms of milk sickness or are graz- 
ing very largely on the rayless goldenrod. 
During the winter of 1922-23 a very interesting series of cases 
of human milk sickness in the Pecos Valley was reported to the 
Department of Agriculture by W. H. Enneis, field agent of the 
United States Public Health Service. These patients showed all 
the typical symptoms ascribed to milk sickness. They had consumed 
large quantities of milk and butter from cows kept in pastures 
which contained little grass and much rayless goldenrod. A suck- 
ling calf kept with its mother in one of these pastures died with 
" trembles." 
Tissues obtained from one of these human cases which terminated 
fatally were examined by Clawson, who has done the microscopic 
work on tissues of animals killed by Aplopappus, and found to cor- 
respond in pathological character to similar tissues from animals. 
EFFECT OF EXERCISE ON ANIMALS 
In the experiments at Roswell four of the cattle and one of the 
horses were given exercise during the feeding work. This consisted 
in being driven back and forth in an inclosure, or, in the case of the 
horse, of being ridden. The exercise was of a rather severe char- 
acter. Steer No. 855, which received no exercise before the appear- 
ance of the symptoms, lasted much longer than the others. Horse 
No. 133, which received no exercise before symptoms were noted, 
made a partial recovery; the other horse, No. 132, which was exer- 
cised, died and showed symptoms on a smaller dosage than No. 133. 
In the succeeding work at the Salina experiment station similar 
results were noted, the periods of trembling following more or less 
severe exercise. The effect of the exercise was to precipitate the 
symptoms and probably, by using up the strength of the animals, 
to make ■ them more liable to yield to the effect of the poisonous 
plant. It is a natural inference that in handling animals affected 
by the Aplopappus, recovery is more probable when the animals 
are kept as quiet as possible. In this connection it may be remarked 
that physicians and others who are familiar with cases of human 
milk sickness have often noted that symptoms are frequently brought 
