238 PARASITES OF MAN 



Dr Leidy, of Philadelphia, admitted A. alata among his Entozoa 

 hominis without comment (' Smithsonian Contrib/ for April, 

 1853), but Weinland, of Frankfort, in his list, prefixed a note 

 of interrogation, observing also that it had been " once " found 

 in Ireland (' Essay on Tapeworms/ p. 88). It is quite clear, 

 therefore, that these authors did not believe that the Ascaris 

 mystax was a human parasite. Those who doubtfully accepted 

 Bellingham's A. alata did so under the impression that what- 

 ever it was, it could not be regarded as the common Ascaris of 

 the cat. In the new edition of Davaine's ' Traite/ A. alata is, 

 to my surprise, still retained as a separate species, and there is 

 no mention of the occurrence of A. mystax in man. From what 

 has recently been written- by several continental helminthologists 

 (Leuckart, Heller, and others), I rejoice to think that it is not 

 necessary for me again to advance the really superabounding 

 proofs that Bellingham's A. alata was nothing more than A. 

 mystax. It has at length been admitted by almost all who are 

 competent to form an opinion, that the memoir originally com- 

 municated to the ' Lancet/ in 1863, and subsequently introduced 

 into the text of my introductory work, finally settled the ques- 

 tion of identity. It was through the donation of Dr Edwin 

 Lankester and Mr Scattergood that I was enabled at the time 

 to announce the third instance. of the occurrence of this parasite 

 in man, and since that date several other instances have been 

 brought under public notice. Not less than seven cases have 

 now been noticed in which this little lumbricoid of the cat 

 and dog has been found in man. For one good human specimen 

 I am indebted to Dr Morton. In the above list I include 

 Heller's specimen, and the one from Greenland sent by Steen- 

 strup to Leuckart. According to Bering's observations this 

 worm grows with remarkable rapidity. Worms obtained from 

 a puppy only six days old measured from ^" to l s " in length. In 

 a twelve- day-old puppy they reached nearly an inch in length, 

 and in a month the growth was up to four inches. Females 

 only 1J" in length already contained eggs, and males only f" 

 long had acquired their spicules. Three weeks therefore, 

 would be amply sufficient for the completion of sexual maturity 

 within the feline or canine host. We do not know, however, 

 whether or not a temporary host is necessary for the larvae prior 

 to their introduction into the cat or dog. Hering thinks that 

 a direct infection by the ova is sufficient ; but he gives no proof 

 of the truth of this hypothesis. " Leuckart (as quoted by Heller, 



