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caeinic blood, can transmit the plague during the act of sucking and 

 that certain individuals suffering from a temporary obstruction of 

 the proventriculus were responsible for most of the infections obtained 

 and probably for all. In a proportion of infected fleas the develop- 

 ment of the bacilli was found to take place to such an extent as to 

 occlude the alimentary canal at the entrance to the stomach. Fleas 

 in this condition can suck blood since the pump is the pharynx but 

 they only succeed in distending the contaminated oesophagus, and on 

 the cessation of the pumping act some of the blood is forced back into 

 the wound, carrying with it plague bacilli. Fleas suffering from 

 obstruction do not necessarily perish and after a few days the culture 

 obliterating the lumen of the proventriculus may disappear and the 

 passage become open again. Since however they are incapable of 

 imbibing fresh fluid, they are in danger of drying up if the temperature 

 is high and the degree of saturation of the atmosphere low. The 

 authors suggest the possibility that this fact may to some extent 

 explain why in India epidemic plague is confined to the cooler and 

 nioister seasons, and particularly why the epidemics are abruptly 

 terminated on the onset of the dry weather. 



Bacot (A. W.). On the Survival of Bacteria in the Alimentary Canal of 

 Fleas during Metamorphosis from Larva to Adult. — -//. Hygiene, 

 Ccnnbridge, Plague Sifjjplentenf III. 14th Jan. 1914, pp. 655-664. 



In this paper the author describes experiments undertaken to decide 

 (a) if the gut of the flea- larvae may become infected with bacteria 

 that are present in the food on which they are nourished, e.g., the 

 faeces of their parents ; and (6) if these organisms can survive within 

 the gut during the metamorphosis from larva to pupa and pupa to 

 imago. The fleas were artificially infected during the period of active 

 larval life and examined for the infecting organism during their various 

 stages, as active larvae, resting larvae taken from cocoons, pupae, 

 and adults. The infecting organisms used were : — B. pgocyaneus, 

 Staphi/lococciis aureus, S. alhus, B. enteritidis (Gaertner), B. violaceus 

 and JB. pestis. Full details of the experiments and the results are 

 given, and by them it is shown (1) that the ahmentary canal of the 

 flea larva may become infected with the following bacteria if mixed 

 with its food, viz.: — B. pgocyaneus, B. enteritidis, S. albus, and *S'. aureus ; 

 (2) that an infection of the larval gut may persist until the resting period 

 of the larva in the cocoon ; and (3) that there is no satisfactory 

 evidence that such infection can survive the pupal stage. 



It has been shown in another paper that flea larvae thrive on a diet 

 composed of their parents' faeces and that for some species it is a 

 normal, perhaps a necessary, source of food. Verjbitski states that 

 B. pestis is to be found in the faeces of four different fleas, fed on animals 

 suft'ering from plague. The conditions in the alimentary canals of 

 flea larvae do not, however, appear to be very favourable to the growth 

 of B. pestis. In larvae of Ceratophyllus fasciat us, the number of cases 

 in which the microscopic examination gave a positive result was very 

 small, and the bacilli few and scattered. No trace was found of the 

 massed multiplication which is so noticeable a feature in infected 

 adult fleas. An interesting contrast to the non-survival of bacteria 

 in the flea's gut after the larval stage is afforded by the Diptera, an 



