48 



contains many references to the presence of nematodes in human 

 cancers, but it lias generally been assumed that such concurrence 

 was accidental. Borrel has held that Deviodex, nematodes and 

 Cysticercus may be the carriers of an unknown virus and has con- 

 nected them with the tumours of mice ; he has also found 

 Demodea- in early epithelioma of the face and in carcinoma of the 

 breast in the human subject. Tsunoda has shown that Demodex 

 may exist in the nipples of women without necessarily producing- 

 cancer ; and Haaland has found the mammary glands of old mice 

 to be frequently infested witli nematodes, which appeared to 

 set up interstitial changes which might be the forerunners of 

 malignant growth. Prof. Fibiger, of Copenhagen, communicates 

 to i\\e Berliner KUnische Wochenschrift, of 17th February 1913, 

 the results of a long series of observations on rats which tend to 

 show that a nematode parasite may give rise to malignant tumour 

 in these animals and that the intermediate host is the cock- 

 roach. 



He made autopsies on three rats in 1907, in the course of some 

 investigations on tubercle, and found their stomachs to be the 

 seat of large papillomatous growths, probably malignant in 

 character, injection of the material of which into other rats 

 yielded negative results. Histological examination of the 

 tumours revealed the presence of an hitherto undescribed species 

 of nematode. A further examination of no less than 1,144 rats 

 resulted in the finding of only 11 which showed anything 

 approaching the conditions originally found and none in which 

 those conditions could be said really to exist. Nematodes were 

 found in 23 cases, but none resembling those found in the 

 original three rats. With great difficulty these three rats were 

 traced to Dorpat, in Russia, and a communication from Galeb to 

 the effect that the cockroach, Periplaneta orientah's, was the 

 intermediate host of a Filaria found in the stomachs of rats, led to 

 the investigation of a large number of Avild rats (Mvs decumanus) 

 in whose stomachs this cockroach was found ; no nematodes were 

 however discovered. Rats from a sugar-refinery, which had fed 

 upon another species {Periplaneta americana), yielded positive 

 results; in 40 cases out of 61, nematodes w^ere found; in 18, the 

 stomachs showed pathological changes; and 9 shov/ed advanced 

 tumours of the same type as those originally found, which was 

 regarded as strong j)rimd facie evidence of a connection between 

 the nematode, through the cockroach, and the disease. Fifty- 

 seven rats bred and reared in the laboratory were then fed on 

 P. americana from the sugar-refinery, during periods varying 

 from 5 to 25 days, the largest number given to any one animal 

 being 94. These rats were isolated and only examined when they 

 died, with the result that nematodes were discovered in 54 cases; 

 in 18 of these there was no disease, but in 36 pathological changes 

 had occurred ; these were very marked in 7 cases and identical 

 with those originally observed. Eggs were found in the excreta, 

 but no embryos, and none developed even when kept for 

 6 months, nor could rats be infected with these eggs ; the cock- 

 roach was necessary for the development of the embryo. Experi- 

 ments on the transfer of these eggs to the previously nematode- 

 free cockroach (Periplaneta orient alts) were perfectly successful; 



