THE MICROSCOPE. 281 
that Mr. Steele was specially deputized to investigate and treat the 
disease. Mr. Steele, says the Philadelphia Medical News, set to work 
with thermometer and microscope, and showed that the disease 
was a true relapsing fever, probably resembling closely, although 
not absolutely identical with, the relapsing fever of man. Experi- 
ments proved the communicability of the disease by ingestion and 
inoculation to the dog, horse, mule and monkey, and examination 
of the blood by the microscope revealed the existence of a parasite 
of the nature of a spirillum, very similar to the form found in the 
relapsing fever of man, and, like it, alternately disappearing dur- 
ing the relapses and intervals of the fever. 
DEVELOPMENT OF FiEas. Mr. George Harkus has succeeded 
in obtaining the whole process of the development of the flea from 
the laying of the egg up. He undertook to begin his experiments 
with two egg-laden females in a box, but the only result was a 
fierce battle that compelled separation of the two at once. Each 
individual laid a batch of from three to twenty-four eggs—the 
average was about a dozen—white and oval. Each end of the oval 
appeared through the glass surrounded by a spiral whorl of oval 
punctures, eighty at one end and and forty at the other. The eggs 
were so nearly transparent that the whole process of development 
could be easily watched, and the exhibition, to judge from the 
warm terms in which it is described, must have been extremely in- 
teresting. The larve resembled elongated little worms, were desti- 
tute of feet, and kept up the usual wiggling motion of their kind. 
They absolutely refused to be fed, and usually died in a few days, 
so that very few crysalides were obtained. 
Perhaps if they had been given their natural way of feeding, 
whatever that may be, the success might have been better. Any 
exposure to cold or damp was immediately fatal. The larve, as 
the pupa stage was approached, assume a red hue, and, about eight 
days from hatching, spin a cocoon like a fluffy speck of white cot- 
ton. The threads are closely woven and of extreme tenuity, and, 
when attached to a textile material of similar color, must be very 
difficult of detection. 
A cocoon was opened after the inmate had divested itself of 
the pupa-case, but stil! remained enveloped in a filmy transparent 
integument. This pellicle covered the insect completely, following 
each leg and antenna continuously. ‘ About four weeks is re- 
