12 Mindeskrift for J. Steenstrup. XXV. 



fed on cockroaches, the nematode was not observed. The worm lives in the mouse quite 

 in the same way as in the rat; it produces inflammation, prohferation and growth, 

 occasionally associated with papillomes in the pavement epithehum of the fundus of 

 the stomach and in the gullet. As far as can be seen from the experiments till now, 

 the anatomicai changes in mice are perhaps in some respects slightly different to the 

 changes found in the rat, e. g. the nematode in mice seems more often to invade the 

 deeper coats of the epithelium, sometimes also the deepest layers of the ventral wall. 

 Development of real cancer has not yet been observed. Also in mice the nematode reaches 

 sexual maturity and typical ripe eggs have been found in all the cases without 

 exception — in the excrements of the mice, c. 2 months after the first feeding on 

 cockroaches. 



Also transmission of the nematode to r ab bit s has given positive results. From 

 the ''"'/4 till the ^/5 1913 8 rabbits were fed on 25 P. americana each, infected with rat's 

 fæces containing eggs. 



Rabbit Idied^'/e 1913 in the gullet 7 Spiroptera (5 d", 2 9) 



_ 2 - «l,o - - 



— 3 — i«/io - - 



_ 4 _ . . _ 



_ 6 _ . . _ 



_ 7 _ . . — 



_ 8 — - - - 



No pathological changes were found in the gullet or mouth or tongue. The stomach 

 was normal and contained no Spiroptera; eggs were not observed in the fæces. ^) 



Experiments on guinea-pigs gave a similar result. From the ^^U till the */5 

 1913, 8 guinea-pigs were fed on 20 specimens of the P. orieritalis each, infected with 

 Spiroptera on eating rat's fæces containing eggs. In 6 guinea-pigs, which died spon- 

 taneously or were killed the ^^/s, V? and ^Vio 1913 respectively, no nematodes were 

 found. In 2 guinea-pigs killed the ^Vio 1913 one male worm was found in the gullet 

 of one of the animals, one female in the gullet of the other; apart from that the gullet, 

 tongue, mouth and stomach were normal. Nematodes were not found elsewhere, in 

 the fæces no eggs could be found. 



The Spiroptera in question, thus, is not only able to live in wild rats {M. decuma- 

 nus, M. rattus) and in white and black and white laboratory rats, but is very easily 

 transmitted to white laboratory mice, rabbits and guinea-pigs. 



^) In later experiments eggs have been observed (addition during the proof reading). 



