30 
Rickettsia-fo’fe Parasite of (Jimex 
tubule and no doubt the stage of the parasite in the infected cells affects the 
readiness with which it is found. 
Motility. 
A study of fresh wet preparations by either transmitted light or dark 
ground illumination failed to reveal any signs of motility. 
Staining. 
The most effective staining process tried is the slow method with weak 
Giemsa stain as generally employed for Rickettsia work, viz. 1 drop of 
stain to 1 c.c. of distilled water applied for 10-24 hours. All the forms are 
decolourised by Gram’s method; the rod and thread forms are only faintly 
stained by the fuchsin counter stain. Strong fuchsin produces only a slight 
effect on the long forms and does not satisfactorily stain the minute coccal or 
diplococcal bodies. With Giemsa’s stain the parasite does not react uniformly, 
the character of the tissues in its immediate vicinity apparently exercises an 
influence on the staining process. Where infected cells have been ruptured 
immediately prior to fixation or if the parasite is included in unbroken cells 
the long forms stain more intensely than when they are free. In the 
former situation the stained organism is purple, or if red, shows a gradation 
to the purple of the internal granules instead of an abrupt transition. It 
would appear that once the bacillary forms are removed from their natural 
habitat they rapidly undergo some change which causes them to stain badly. 
Cultivation. 
Attempts were made to cultivate the organism on artificial media. All the 
ordinary media were tried, aerobically and anaerobically, and in addition 
Dorset’s egg medium, Noguchi’s medium for spirochaetes, Krumwiede and 
Pratt’s (1913) semi-solid medium which is successful in the cultivation of 
B. fusiformis, and the body juices of a lepidopterous pupa (Hadena oleracea), 
but in each case without a positive result. 
In view of the remote possibility of the organism being a stage in the 
developmental cycle of a spirochaete, some mice were inoculated b v scarification 
and subcutaneous injection with infected Malpighian tubes of the bug but no 
spirochaetes appeared in the blood. 
Evidence of the hereditary character of the parasite. 
In the absence of evidence that the parasite had any second host, theoretical 
considerations based on the feeding habits of Cimex lectularius suggested that 
the organism must be passed on through the egg. An examination of smears 
made from the alimentary system of newly hatched unfed bugs showed that 
the latter were infected. Eggs washed in 2 per cent, lvsol for five minutes 
and then in sterile salt solution contained both rod and thread forms, the 
