LIFE HISTORY OF. ASCARIS LUMBRICOIDES. 7 



ol)servations have been made as to the slight effect upon Ascar-ls eggs 

 of \arious substances that ai-e very destructives to protophisni. For 

 example, Galli- Valeric (1914) succeeded in developing the eggs to 

 a stage containing vermiform embryos in solutions of sulphuric, hy- 

 drochloric, nitric, and acetic acids 50 per cent or less in strength, in 

 saturated solutions of copper sulphate, iron sulphate, and copper 

 acetate, and in 50 per cent antiformin. In experiments with full- 

 strength antiformin we have found that the sliells of eggs contain- 

 ing motile embryos are dissolved by this substance, but the thin mem- 

 branous lining of the shell remains intact. Kept in antiformin within 

 this membrane the embryo may still be active at the end of 5 days, 

 but if the membrane is burst by applying pressure the embryo is in- 

 stantly killed by the antiformin. 



We luive kept Ascaris simni eggs containing vermiform embryos 

 alive for several hours in carbolic acid, and embrv'os were still active 

 in eggs kept 5 weeks in crude petroleum and in petrolatum. In eggs 

 kept 10 weeks in crude petroleum no living embryos were seen, and the 

 shells of most of the eggs Avere collapsed, but in most of the eggs kept 

 the same length of time in petrolatum the embr^^os were active and 

 very few eggs with collapsed shells were observed. 



In -view of the resistant nature and impermeability of the shell of 

 the Ascaris egg it is evident that ordinary methods of disinfection 

 by the application of chemical agents in more or less dilute solutions 

 are of little or no use in preventing the spread of infection. Accord- 

 ing, however, to results obtained by Wigdor (1918) and unpublished 

 results of experiments by Dr. Raffensperger and Miss Cram, phenol 

 solutions are destructive to the eggs of Ascaris (or Toxascaris in the 

 case of Wigclor's experiments), and it is possible that phenol disin- 

 fectants may prove useful under some conditions in the control of 

 AscaHs. 



AVENUE OF INFECTION WITH ASCARIS. 



Infection with Ascaris has been shown hy repeated experiment to 

 be the result of swallowing eggs containing fully developed embryos. 

 The possibility of natural infection in other ways than by the swal- 

 lowing of eggs, however, is not absolutely excluded. Martin (1913) 

 injected eggs of Ascaris equorum containing active embryos beneath 

 the skin of a guinea pig. When the animal was killed 11 days later 

 many empty eggshells were found at the site of injection, showing 

 that the eggs had hatched. The fate of the embryos was not deter- 

 mined. Martin made similar experiments with the eggs of A. eqivo- 

 imm and A. vitulorum on a dog, a rat, and guinea pigs, with similar 

 results. We have repeated Martin's experiments, using eggs of 

 A. suiiTTi containing active embryos (Experiment No. 13). 



Our experiments show that if introduced beneath the skin Ascaris 

 eggs will hatch and that within a few days the larvae will appear in 



