EEVIEW — TROPICAL MEDICINE, ETC. 191 



As regards treatment, their experiments showed that immune serum, whether derived Spirochsetes 



from horses, monkeys or rats, has no appreciable vahie either in preventing tlie occurrence and Spiro- 



of the attacks in susceptible animals or in curing the disease once contracted. The incubation chaetosis— 

 period may be prolonged to a greater or less extent, but the inoculation of infective blood is coniinned 



always followed by infection. 



In one case hyper-immune serum, i.e. serum derived from animals after a varying 

 number of inoculations with spirochiEtal blood, used as a preventive, prolonged the incubation 

 period very markedly and moderated the severity of the attack. Similar horse serum used 

 as a curative agent proved itself of no pronounced value in the treatment of the disease in 

 monkeys. A slight inborn immunity of short duration was noticed. 



Other points elucidated were that the spirochete of African tick fever is of a species 

 differing from iS'. ohermcieri, since each confers a relatively active immunity against itself 

 but not against the other, that 8. dtttioni passes through the placenta from the circulation 

 of the mother to that of the foetus, that the course of the disease in spleenless animals does 

 not differ in any way from that noted in normal animals, and that spirochsetes when 

 disappearing from the blood do not rest solely in the spleen. 



Experiments of tick feeding and splenectomy during the incubation period showed that 

 spirochsetes are present in the peripheral circulation in an infective stage on the first day 

 after ticks are fed on a susceptible animal, and that : — 



1. lu splenectomised animals, the spiroolistes disappear from the peripheral circulation after the attack as 

 promptly as in normal animals and relapses occur in the ordinary way. 



2. When the spleen is removed shortly after the spirochsetes have disappeared from the peripheral circulation 

 after the tirst attack, the relapses occur as in the controls. 



3. During the incubation period, after ticks have been fed on a susceptible animal, the spirochstes do not 

 develop in the spleen as the site of election. 



4. Active immunity against reinfection is not influenced by the spleen. 



Dealing with stained specimens, they note that the terminal flagellum of some observers 

 is the periplast of the parasite drawn out to a pointed extremity at one end of the spirochaete, 

 that the chromatic core does not stain evenly, and that peculiar forms are seen most 

 often in the " decline " blood. The core may be broken up into from six to eight small 

 portions, which stain deeply by Giemsa's method. In films made from the liver and spleen 

 they found a curious form in the shape of a spirochaete coiled up into a small compass 

 surrounded by a well-stained membrane, the whole structure being about three-quarters the 

 size of a red blood cell. They think this may be an encysted stage. 



Together with Todd,^ these authors also found that Gimex lectularins, the bed-bug, is 

 probably unable to transmit S. dnitoni or <S'. ohermeie.ri, and therefore it cannot be an 

 important factor in the causation of epidemics of relapsing fever. 



BreinF has further pursued the study of the morphology and life-history of 

 S. duttoni. He employed dry films and the Giemsa stain. Wet films were found to present 

 no advantages. He failed to demonstrate peritrichal flagella, and notes the frequent presence 

 of swellings during the stage of "decline," as also the presence of a small unstained 

 transverse band at about one-third of the length of the parasite. No true undulating 

 membrane could be demonstrated. The division of /SI. duttoni was, as a rule, found to be 

 transverse, though occasionally longitudinal division was observed, as was also an appearance 

 suggesting conjugation. 



Allusion is made to Prowazek's discovery of intra-cellular stages of iS. gallinarum in 

 the red blood cells (see also special article on "Spirochsetosis of Fowls," Third Report), and it 

 is noted that the same phenomenon in rare instances was observed just before the crisis 

 in )S'. duttoni. The formation of coiled and skein-like forms at this time in the spleen and 

 bone marrow, rarely in the liver, is described as is the phagocytosis which they undergo in 

 the spleen, or, if the spleen be removed, in the liver. Some, however, escape destruction 

 and become surrounded by a thin cyst wall, the interior of the cyst being filled with a faintly 

 blue-stained plasma. The shape of the parasite becomes indistinct until only a few small 

 red granules persist. These may be the forms which can pass through a Berkefeld filter and 

 give rise to a fresh infection. The life-history of the spirochaete is thus summarised : — " Just 

 before the crisis the spirochaetes disintegrate, certain of them coiling up into skeins, the 



' Loc. cit. 



^ Breinl, A. (November 9th, 1907), " On the Morphology and Life-History of Spirochseta Duttoni." Annals of 

 Tropical Medicine and Parasitology, Series T.M., Vol. I., No. 3. 



