COCKROACHES 21 



according to the circumstances, and there appears 

 to be an intelligent method of overcoming every 

 difficulty.-'^ 



Apart from animals which eat it, there 

 are a number of parasites which infest it, 

 beginning with the parasitic beetle Symhius 

 hlattarum, whose wingless females attach 

 themselves to the bodies of the cockroaches 

 and feed upon their tissues. Then occasion- 

 ally a round-worm, Filaria rhytipleurites, 

 whose sexual stage is passed in the rat, is 

 found in its larval stage in the fat bodies of 

 the cockroach. 



Two years ago Dr. C. Conyers Morrell 

 undertook some investigations and observa- 

 tions as to what part, if any, cockroaches 

 played in the dissemination of pathogenic 

 microbes, his object being, as he says, ' first 

 to ascertain what bacilli belonging to the 

 colon group are likely to be conveyed to food 

 and milk by this insect, and secondly to find 

 whether known bacteria and moulds can be 

 transmitted by the faeces.' Dr. Conyers Mor- 

 rell's experiments were conducted on one of 

 the Union Castle liners sailing to South Africa, 

 and the insects which were investigated were 

 collected only from the larder or passages 



^ The Transformation of Insects, by P. M. Duncan. London : 

 Casaell, Petter, Galpin and Co., 1882. 



