Johannes Fibiger and Hjalmar Ditlevsen: Spiroptera neoplastica n. sp. 27 



When liberated, the larva will immediately seek a spot on the mucous membrane 

 fit for invasion. There is nothing to show that after this it changes its place; fully 

 developed worms may thus be found in the mucous membrane of the oesdphagus as 

 well as in the root of the tongue ; most of the larvæ, however, are swallowed and 

 passed with the food into the stomach where they are to be found in the sqamous- 

 celled epithelium of the cardiac portion. 



During the first period the larvæ seem to grow but very slowly, having reached 

 after 10 days only double the length of that which they had on the transmission. 

 Then, however, the growth is quickened very considerably ; a few weeks after the 

 feeding they measure about ten times the length of the encysted larva. 



Experiments as to the growth and^'development of the larvæ were carried out in 

 the following way: On some fixed day a number of rats were fed on infected cock- 

 roaches; the next day one of the rats was killed and its stomach and oesophagus 

 was examined, and so on. The larvæ from the various rats were examined and 

 measured, and thus an inventory was procured which gave a view of the case 

 concerned. Besides the faet already described, these experiments, however, permit 

 no further conclusions as to the growth of the larva, the comparative length of oeso- 

 phagus and the development of the genital-app aratus, — the material being too limited. 



In order to get hold of the larvæ the mucous membrane was scraped with 

 a scalpel but this method only gave very few larvæ sometimes but one or two. 

 Greater series of measurements were thus precluded. If measurements were undertaken 

 on a larger scale an inordinate number of rats would be required. 



The following table gives a view of measurements of the length of the larvæ, 

 carried out on live specimens from the stomach or from oesophagus of the rat. 



Larva 1 day after the feeding 1247 /t stomach 



— 2 days — — 1056 fx oesophagus 



— 3— — — 122Q[i stomach 



— 4 — — - 891// — 



— 6- — - 12bb[i - 



— 8— - — 1750 /* - 



— 10 — — — 2268 /t - 



— (female) 16 — — — 11,7 mm. — 



After having been in the stomach of the rat for about 8 days the tail of the 

 larva presents itself as that of the fully developed worm. A larva in this stage of 

 development has been observed in the moult; the tip of the tail was still trifid, but 

 after the ensuing moult the tail would turn out single ; the hind part of the worm had 

 drawn somewhat back from the old cuticula, which was here already loosened, and 

 the new shape of the tail appeared within. In another larva the tail 10 days after 

 the transmission to the stomach of the rat still presented the bifid stage. 



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