Johannes Fibiger and Hjalmar Ditlevsen: Spiroptera neoplastica n. sp. 5 



Out of 61 rats (M. decumanus) caught in this locality and kept isolated in the institute 

 — most of them until death, 40 rats presented the nematode in the epithelium of the cardiac 

 portion of the stomach. Pathological changes were found in 18 among these 40 rats, in 9 cases 

 as marked papillomatous tumours of the same type as described above, while in the rest of 

 the cases the process must be considered a prehminary stage of true new growth. It was 

 further determined that the nematode could not only be found in the cardiac portion of the 

 stomach but also in the epithelium of the oesophagus, occasionally also in the epithehum of ' 

 the tongue and in the mucous membrane of the mouth. 



Observations made on rats fed on cockroaches (P. americana) caught in the refinery, 

 gave the foUowing result: 



For these experiments 4 wild brown rats from the neighbourhood of Copenhagen and 53 black 

 and white rats born and bred at the new anatomical-pathological Institute of the University 

 were used. The modern, and hitherto unused stables here did not at all harbour cock- 

 roaches. The rats were fed on cockroaches for one or 2 periods, every period being of 3 — 70 

 days duration. The number of cockroaches used as feeding-material varied, 2 rats were given 

 c. 100, the rest less. The rats with a few exceptions were not killed unless getting into agony. 

 On the whole, the experiments gave the fol lo wing results: In 3 rats the stomach presented 

 no pathological changes and especially no nematodes. On the other hånd parasites were found in 

 different numbers in the remaining 54 rats, 37 of which presented pathological changes simul- 

 taneously. In 11 cases the process appeared to be but slightly marked, in 27 cases a .higher 

 stage of development was reached, which in 7 cases consisted in enormous tumour-growths of 

 the described type. 



The nematode and eggs found in these rats corresponded to those observed in the rats from 

 Dorpat and in the rats caught in the sugar refinery. Most unfortunately — however — the 

 sugar refinery was destroyed by fire in February 1912, and experiments consequently could not 

 be carried on, as at this point of time no other locality in Copenhagen or elsewhere seemed to 

 harbour the P. americana. 



The results of all series of experiments are seen from the table: 



Sort of rats 



Number of 



rats 

 examined 



The worm 

 found in 



The worm found ; True 

 coincident with newgrowth 

 path. changes in i found in 



Wild rats: 



m. decumanus 



m. rattus 



m. alexandrinus 



Black and white laboratory rats 



Total... 



m. decumanus from sugar refinery 



Black and white laboratory rats fed on P. 

 americana from sugar refinery 



Total... 



844 



21 



2 



