May 13, 1922] 



NATURE 



619 



School. He did not enjoy the privilege of a scientific 

 ( ducation, and on leaving school he became a clerk in 

 1 commercial house in the City, where he remained until 

 .orty-five years of age. Notwithstanding, his was a 

 finely-trained scientific mind. Perhaps he was to the 

 manner born. From boyhood he had been an enthu- 

 siastic entomologist, and despite his scanty leisure he 

 became a lepidopterist of repute. Bacot was, however, 

 no mere collector. Nor was he satisfied with observa- 

 tions and description of structure. It was the life 

 history and bionomics of insects which attracted him 

 and the use that could be made of entomology in the 

 wider problems of heredity. He had an extraordinary 

 knowledge of insects and a wonderful sympathy with 

 them. Unfortunately his literary powers were slight, 

 but his conversation on the subject of insect life was as 

 fascinating as any of the writings of Fabre. 



In the breeding of insects Bacot was extraordinarily 

 successful, and some of the most important of his earlier 

 contributions to entomological science were undertaken 

 as studies in the laws of inheritance. Notable amongst 

 these, which are scattered through the pages of the 

 Entomological Review and the Proceedings of the 

 Entomological Society, is his work with Prout " on the 

 effects of cross breeding of different races of the moth 

 Acidalia virgularia," which appeared in the Proceedings 

 of the Royal Society,' 1909, 



The opportunity for Bacot to devote the whole of his 

 energies to scientific work arose in the following way. 

 The Commission for the study of plague in India having 

 arrived at the conclusion that the essential means of 

 spread of bubonic plague was the rat-flea, it was 

 obviously advisable to obtain as much knowledge of the 

 bionomics of these insects as possible. Bacot was 

 invited to undertake the investigation. He was still 

 occupied in clerical work, and at first he demurred on 

 the score of both lack of time and lack of any special 

 knowledge of fleas. His modesty was, however, over- 

 come by the assurance that innocence of all but the 

 external features of the siphonoptera was fairly general 

 and the diflSculty due to want of leisure was, to some 

 extent, met by the provision of an assistant to carry 

 out his instructions while he himself was at his office. 

 F The results of eighteen months' work was highly 



satisfactory. The whole life history of the commoner 

 rat-fleas was ascertained with great completeness, and 

 the influence of all the significant environmental con- 

 ditions upon their longevity and rate of propagation. 

 The adverse effects of various treatments which might 

 conceivably be used in combating plague were also 

 determined. The observations formed the subject 

 matter of a monograph on the bionomics of the common 

 rat-fleas occupying 200 pages of the Journal of Hygiene. 

 The work is a model of accuracy, clarity, and complete- 

 ness, and at once stamped Bacot as an observer and 

 experimenter of high quality. 



The value of such a man to medical discovery was 

 apparent, and in 191 1 a special position was created for 

 him at the Lister Institute, and he was invited to 

 become its entomologist. He accepted the position, 

 and henceforth was able to devote himself entirely to 

 science and to apply his entomological knowledge and 

 experimental skill to problems in epidemiology. 



In the congenial atmosphere of the Institute, with 

 well-equipped laboratories at his command, Bacot 



NO. 2741, VOL. 109] 



rapidly became expert with bacteriological and histo- 

 logical techniques, and was able to collaborate with his 

 medical colleagues with completeness and to take a full 

 share in the experimental work and in the responsibility 

 for the results. 



The Indian Commission had demonstrated fully that 

 the agent of infection in the case of bubonic plague is 

 the rat-flea, but the modus operandi it had been unable to 

 determine. It was some years later (1913) that Bacot 

 and Martin showed experimentally exactly how it 

 occurred. From their observations, the very existence 

 of plague seems to depend upon the accidental property 

 of the plague bacilli of growing in the form of a coherent 

 sticky mass. When the flea inflates its stomach with 

 the blood of a plague-stricken rat, the bacilli, introduced 

 with the blood, rapidly multiply in the alimentary canal, 

 forming masses of culture. These masses increase 

 quickly in size until they effectually plug the gizzard 

 at the entrance to the stomach and grow forward in the 

 gullet. A flea with its alimentary canal obstructed 

 by this means suffers from a thirst which it is unable 

 to quench, and bites with more persistence and much 

 greater repetition than normally. The entrance into the 

 stomach being obstructed, the efforts of the insect only 

 inflate its oesophagus with the fresh blood, some of which 

 fuiis back into the wound well dosed with plague bacilli, 

 as soon as the action of the insect's pharyngeal pump 

 ceases. What remains serves as culture media for plague 

 bacilli to grow upon, and the result is, as Bacot was able 

 to demonstrate by some wonderful sections, a flea 

 contaminated, literally, up to its mouth. The plague 

 bacillus passes no essential part of its life history in the 

 body of the insect, such as is the case with the malaria 

 parasite. It is an instance of spurious metaxeny, but a 

 flea in the condition just described cannot fail to carry 

 infection once it is let loose upon a susceptible animal. 



In 1914 Bacot proceeded to Sierre Leone as the 

 entomological member of a Yellow Fever Commission 

 sent out by the Colonial Office. The original scheme 

 of work was upset by the removal of the medical 

 members owing to the war. Bacot, however, remained 

 for one year and studied the bionomics of Stegomyia 

 fasciata, the mosquito which is the transmitter of yellow 

 fever, and produced a very complete and detailed 

 monograph upon the life history of this insect in West 

 Africa and the various conditions which modify its rate 

 of propagation. 



Bacot returned to England in August 1915 and at 

 once threw himself into the intensive study of lice and 

 the most practical method of ridding our soldiers of 

 these vermin in view of their depredations and the 

 incident dangers to health therefrom. The value of 

 Bacot's work in this direction was great, and the ex- 

 periments on which his conclusions were based were 

 always made upon himself under conditions similar to 

 those actually encountered in the field. The recom- 

 mendations were soon found to be sound and practicable 

 ones, and in 1916 he was asked to accept the position 

 of honorary entomological adviser to the War Office. 

 In this capacity he was constantly consulted by military 

 sanitarians, who were bombarded with various nostrums 

 and devices for dealing with the louse problem. 



In 191 5-16 our troops in France were found to be 

 suffering from a new disease, " trench-fever," which 

 soon proved to be a principal cause of medical invaliding. 



