468 
Eepobt of the Assistant Chemist of the 
free use of fore-legs and a general weakness, and they would only- 
move about when forced to do so. The mice with backs arched 
remained quiet, with nose drawn down between the fore-legs and 
resting the foreheads upon the bottom of their cage. There was no 
vomiting or purging, and they gradually grew better and finally 
recovered. 
On receiving the cream I at once forwarded a portion of it to Dr. V. 
C. Vaughan, of Michigan University, Ann Arbor, Mich., who was the 
first to thoroughly investigate the nature of tjiese poisonous products 
in cheese and in cream, and who gave to them the name tyrotoxicon. 
Dr. Vaughan kindly examined this, and under date of July 11, wrote 
me as follows: 
"I will give you the results of the analysis of the cream which you 
had the kindness to send me. I tested for tyrotoxicon only, supposing 
that you had examined it for other poisons. 
"Some distilled water was added to the contents of the bottle, and the 
whole was filtered. The filtrate gave the reaction with sulphuric and 
carbolic acids very distinctly ; but, as you know, this reaction may be 
. due to tyrotoxicon (diazobenzol) or to nitrates or nitrites. The filtrate 
was then neutralized with sodium carbonate and agitated with an equal 
volume of ether. The ether was removed and allowed to evaporate 
spontaneously. To this residue a little water and a few drops of nitric 
acid were added, and then an equal volume of a saturated solution of 
potassium hydrate, and the whole heated on the water-bath, when the 
oeautiful plates of diazobenzol (tyrotoxicon) potassium hydrate were 
formed. 
"After having obtained these crystals, I was unavoidably called away 
from my work for a few hours, and on my return I found that the 
crystals had all decomposed. So I did not have the opportunity of 
making other and confirmatory tests ; but I should have no hesitancy, 
from the tests which I did make, in saying that diazobenzol (tyrotoxi- 
con) was present." 
This confirmed the result of my own examination and conclusively 
demonstrated that tyrotoxicon was present, and, with the experiments 
made upon mice, showed the cause of the sickness to be due to this 
product. 
At a later date Dr. Vaughan wrote me as follows: 
"The action of the poison on the mice, as observed by you, is very 
Interesting. I have obtained exactly the same symptoms with the 
artificially prepared diazobenzol on guinea pigs and frogs. In these 
animals there was neither vomiting nor purging, while the same sub- 
stance induced vomiting in cats and dogs." 
The method by which the milk was furnished for the occasion, and 
the mixing together Unit from so many different sources and of 
