ENTOMOLOGICAL NEWS. 359 
1 live tissue is not directly available. A bite 
By after such infection would indeed prove disastrous. 
ft 1 observers have noted in the history of an outbreak 
its  incipiency that it becomes effective in this wise: First, 
yet : erved that an unusually large number of rats in a cer- 
locality come out into the «open and, acting queerly, un- 
us of the presence of enemies, die in a short time. Then 
sa : lull of several days, followed by the illness of the first 
ie victions. It is during this lull in the history of a plague 
= mic that there appears to exist an abnormal supply of rat 
_ This latter fact is amply illustrated from incidents in 
Francisco epidemic. In the early part of the cam- 
igr n Dr. William Wherry, Bacteriologist of the San Fran- 
sco. ‘Health Department, collected one hundred and eighty 
eas from two rats sent in from the Latin Quarter, a pest- 
dde J | district. On four rats taken from Meigg’s wharf in 
an F > there were counted approximately two hundred 
ad forty ‘fines. Three of these rats were autopsied and one 
to have a pronounced case of plague, verified by Dr. 
dy, av. ‘s A., clinically and bacteriologically, Under nor- 
$c litions and in districts removed from plague, the rats 
harbor an average of three or four fleas. 
e tions were taken to determine whether rat fleas 
will bite the human. Baker states (Proc. U. S. Nat. Mus. ’05) 
tha rat fleas in America were never known to bite man. Since 
___we know definitely how the plague is transmitted from rat to 
man it must be taken for granted at the outset that man has 
1 1 ten rat flea bitten in many instances, as the San Francisco 
__ Official plague records will show. Specific instances can be 
é cited hy the improvised bacteriological laboratory of the San 
o ar » Health Department hundreds of dead and live ro- 
4 0 toa were brought daily. Fleas from these rats hopped freely 
about the floors and work tables, making things irritable for 
2 4 attendants and health officers. On shipboard nine specimens of 
rat fleas were collected preying on one of the surgeons in the 
United States Public Health Marine Hospital Service. My 
harem experiences contribute the fact that rat fleas taken 
Bp rectly from live rats or even rats which have been dead for 
eae hours, will not bite the human until they have been per- 
» mitted to starve in a test tube for two days or longer. 
