318 ANIMAL PARASITES. 



the youngest Ascaris lumbricoides which I have seen, is a specimen 

 which I expelled from myself in July, 1853, in treatment for 

 tapeworm, which is nevertheless nearly two inches long ; of this I 

 shall speak further on. Opinions, such as those expressed 

 not long since by A. Beauchair and P. Vignier in the 

 ' Gazette de Paris/ 1853, Nos. 29 and 30, are certainly an- 

 tiquated in Germany, and may be passed over in silence. 

 The times are past in which the generatio aquivoca made 

 its appearance, with a peculiar predisposition to worms ; 

 although this view may hide itseM" behind an extremely plausible 

 account of the remaining of the acids in the blood, the formation 

 of neutral salts, dealkalization of the blood with production of 

 weakness, and acid intestinal mucus, or behind fine-sounding 

 theories of the actions of remedies. What is there positive in 

 words like the following? "In the predisposition to worms, the 

 thick mucus of the intestine comes under our consideration in the 

 first place, as, being acid itself, it cannot purify the blood from 

 acids. From a portion of the mucus the worms are produced by 

 generatio cequivoca, with the assistance of asthenia and adynamia. 

 The worms produced, as the analysis shows, are still more acid 

 than the mucus, from which they are produced. Emetics, drastic 

 purgatives, mercury, antimony, and arsenic, certainly kill the 

 worms, but weaken the constitution, and thus actually rouse the 

 generatio aequivoca into activity, and thus cause the formation of 

 worms, &c." This sample will suffice to show how little tenable 

 there is in these last French attempts at the explanation of the 

 mode of production of the Ascarides. 



Unfortunately here we are not even assisted by Bichter's 

 experiments. By his means, indeed, we know that the eggs of 

 Ascarides become further developed, free in the water, and that 

 the embryo is formed here; but hitherto all administrations of 

 these eggs to dogs, pigs, and other mammalia, have been unsuc- 

 cessful. It is true that no human individual has been experi- 

 mented on, and yet the direct transfer of the eggs with the 

 embryos may be sufficient for the perfect development of Ascaris 

 lumbricoides in man. On the other hand, however, it is also 

 possible that there is a previous migration through animals used 

 as human food. 



What more we have to say upon the round-worms in general, 

 may be summed up in few words. The rest follows with the 

 consideration of the species. The general cutaneous covering is 



