10 Mindeskrift for J. Steenstrup. XXV. 



P. americana, in 1 case P. orientalis) microscopical examination of tlie cardiac portion of the 

 stomach showed processes which differed from those found in the other rats. The changes, 

 in faet, here appeared to be true cancerous growths, the mucous membrane 

 and submucosa having changed into a tumour tissue of quite the same 

 type as is generally found in true squamous-celled carcinoma in man. 



In 2 of these rats carcinomatous metastases were observed in a lymph gland and in a 

 lung respectively; in a third case the urinary bladder contained papillomatous growth which 

 was probably a metastase too. Notwithstanding a very careful examination of serial sections 

 neither nematodes nor eggs were found in any of these metastases, being thus metastases in 

 the most strict sense of the term. 



By these investigations carcinomatous tumours giving rise to meta- 

 stases were produced experimentally for the first time, and the hypo- 

 thesis put forward by Borrel and Haaland was thus verified, as it has 

 now been proved, that nematodes play a causal part in the development of cancer in rats ^). 



Further particulars as to description and pictures of the growths and pathological changes 

 described above will be found in the papers previously published by J. Fibiger. 



As only in very few cases bacteria were found outside the most superficial coats of the 

 epithelium of the ventral wall, it seems in advance to be unreasonable to make such microbes 

 responsible for the development of tumour growth. It rather must be referred — as well as 

 the local eosinophily — to some poisonous seere tion of the worm, and the more so, as in the 

 most rats, a rather constant and plain proportion could be stated between the degree of the 

 pathological changes, the number of the parasites and the length of time in which the spiroptera 

 had lived in the fundus of the stomach. 



Owing to the ability of the nematode to produce new growths the name Spirop- 

 tera neoplastica is proposed. 



As a supplement to this summary of the papers previously published, some later 

 investigations concerning the biology of the worm, carried out by J. Fibiger in the 

 anatomical-pathological Institute of the University of Copenhagen will be recorded here. 



As already mentioned it had not been possible — notwithstanding thorough exa- 

 mination — to find the Spiroptera in any other wild Danish rat, than in those caught 

 in the sugar-refinery, where P. americana were found in great numbers. 



On continued examination this result was further confirmed, as the nematode was 

 observed only in one of 3 rats (Mus decumaniis) caught in a sugar-refinery connected 

 with the one mentioned above. 



') Later on, moreover, carcinoma has been produced in the same way in several rats. In 

 one of these rats metastases also were observed. (December 1913). 



