224 SUMMARY OF CURRENT RESEARCHES RELATING TO 



bladder. Asiatic bilharziosis is transmitted by species of Bythinia, 

 Egyptian bilharziosis by BiiUmis, Planorbis, and Melania. Besides 

 Bilharzia heematohium of man there is in Egypt B. bonis in cattle, and 

 Bilharziella polonica in ducks. Leiper has succeeded in artificially 

 infecting monkeys, guinea-pigs, rats, and mice, the animals being placed 

 in shallow water into which large numbers of cercariae had been 

 liberated. The tail is discarded at the moment of infection and the 

 body burrows into the lymph vessels and blood vessels. Thence the 

 parasite reaches the liver where the cercarial body undergoes gradual 

 growth and differentiation. The sexes are first distinguished by the 

 broadening out of the males in the early stages of their growth in the 

 liver. The females commence to produce eggs in six to ten weeks after 

 infection. 



Animals infected with cercariag from Bulinus dyhowslci, etc., always 

 produce adult worms which give rise to terminal-spined eggs only, while 

 those infected with cercariae from Planorhis boissyi give rise equally 

 constantly to lateral-spin ed eggs. In no case do both varieties arise 

 from the same intermediate host. The terminal-spined eggs give rise to 

 B. hsematobium (sensu strictiore), the lateral-spined eggs to B. mansoni 

 (Sambon). The males of B. hsematobium appear to leave the liver 

 early, and to pass down into the finer branches of the mesenteric vessels 

 before they attain maturity. The females found in the gynsecophoric 

 canal are diminutive> The males of B. mansoni remain in the liver 

 until the females in copula begin to lay eggs, and large numbers of 

 lateral-spined eggs are frequently laid in series by coupled worms in the 

 veins even on the edge of the liver. The eggs found in bilharzial 

 cirrhosis of the liver may have been laid there, not carried thereto from 

 the mesenteric vessels as has hitherto been supposed. 



Asiatic Schistosomiasis.* — R. L. Leiper and E. L. Atkinson give 

 an account of their mission to the Far East to investigate the mode 

 of infection in Asiatic schistosomiasis (bilharziosis). Working from 

 Shanghai, they visited many infected districts in China and Japan in 

 search of material for experimental study. The Looss hypothesis of direct 

 infection was discarded in favour of one to the effect that the schisto- 

 stome conformed in essentials to the life-cycle of other digenetic trema- 

 todes. After a search of three months, involving a journey of 1000 

 miles, a dog was found heavily enough infected to yield eggs that 

 could be separated from the faeces with little contamination. 



Specimens of all species of mollusc found were placed in water 

 swarming with Miracidia, and a watch was kept to see whether any of 

 them showed any special attraction for the embryos. One form, named 

 from the locality in which it abounded, Kataijama nosophora, speedily 

 became festooned on head and feet with white specks, which obviously 

 caused great irritation. In many individuals of this species the liver 

 was found ramified with fine tubes (sporocysts) containing cercariae with 

 bifid tails, and with the complete absence of pharynx characteristic of the 

 schistosome larva. The livers of infected snails were teased out, and 

 the cercariae allowed to become free and swim about. Live mice were 



» Brit. Med. Journ., 1915, pp. 1-16 (10 figs.). 



