[Illustration: FIG. 49.--Germs and ova of _Ascaris mystax_. Nos. 1 to 3 magnified 330 diameters and Nos. 4 to 24 magnified 220 diameters. After Nelson.] Into the question of the mode of formation of the ovarian ova, and also into that of the development of the spermatozoa, I do not enter. However unwillingly, I must, in this matter, be contented to refer to Professor Allen Thomson’s classical article ovum (quoted below), to Leuckart’s elaborate analysis (l. c., Bd. ii, s. 76-92), and also, especially, to the exhaustive memoir of Claparède, whose brilliant labors, like those of Henry Nelson, were too early terminated by death. Shortly after graduation Nelson suffered a virtually enforced banishment from his native land. BIBLIOGRAPHY (No. 33).--_Bellingham, O. B._, “On the Genus to which the Worms known as Ascarides belong,” ‘Dublin Journ.,’ vol. xiv, 1839.--_Idem_, “Catalogue of Irish Entozoa,” ‘Ann. of Nat. Hist.,’ vols. xiii and xiv, 1843-44; and in the first part of Charlesworth’s ‘Mag. of Nat. Hist.,’ vol. iv, 1840. See also the address by Dr E. D. Mapother on the “Lives and Writings of O’Ferrall and Bellingham,” in the ‘Dubl. Journ. of Med. Sci.,’ Nov., 1877, p. 471 _et seq._--_Bischoff_, ‘Widerlegung (u. s. w.),’ Giessen, 1853; quoted by Claparède, l. c. _infra_, p. 9.--_Idem_, ‘Bestätigung (u. s. w.),’ Giessen, 1864.--_Idem_, “Ueber Ei-und Samenbildung und Befruchtung bei _Ascaris mystax_,” Sieb. and Köll. ‘Zeitsch.,’ 1855, s. 377; also in S. and K. ‘Zeitsch.,’ 1856.--_Bremser_, ‘Icones helminth.,’ p. 23, tab. iv.--_Claparède, E._, “Ueber Eibildung und Befruchtung bei den Nematoden,” S. and K. ‘Zeitsch.,’ 1857, s. 106.--_Idem_, ‘De la formation et de la fécondation des œufs chez les vers Nématodes,’ Genève, 1859. See also ‘Ann. of Nat. Hist.,’ vol. i, 3rd series, 1858.--_Cobbold_, in ‘Proceed. of the Zoological Soc. of London,’ Nov., 1862.--_Idem_, ‘Brit. Assoc. Rep.,’ 1862.--_Idem_, “On the occurrence of _Ascaris mystax_ in the Human Body,” with figures, ‘Lancet,’ Jan., 1863; and in the ‘Dublin Med. Press,’ Feb., 1863.--_Idem_, ‘Entozoa,’ chap. xi, p. 316, 1864.--_Idem_, ‘Worms,’ pp. 72 and 112, 1872.--_Idem_, in “Obituary Notice of Dr Henry Nelson,” ‘Med. Times and Gaz.,’ 1865 (?).--_Davaine_, ‘Traité,’ l. c., 1877.--_Diesing, C. M._, ‘Syst. Helm.,’ vol. ii, p. 180, 1850.--_Dujardin_ (l. c., Bibl. No. 2), p. 162.--_Frœlich_, in ‘Naturf.,’ xxiv, s. 141 (_Asc. felis_).--_Funke, O._, ‘Lehrbuch (u. s. w.),’ 1857, s. 1299.--_Gmelin_, ‘Syst. Nat.,’ p. 3031.--_Golze_, ‘Naturg.,’ l. c., s. 79.--_Gurlt_, ‘Path. Anat.,’ s. 366.--_Heller, A._, “Darmschmarotzer,” in Von Ziemssen’s ‘Handbuch,’ Bd. vii, s. 361.--_Idem_, ‘Sitzungsb. d. Erlanger phys.-med. Soc.,’ 1872, s. 73.--_Hering_, “Ueber das Vorkommen und die Entwicklung der _Ascaris mystax_ bei jungen Hunden,” quoted by Leuckart from ‘Würtemb. Naturw. Jahreshefte,’ 1873, s. 305-337.--_Kölliker_, in ‘Müller’s Archiv,’ 1843, s. 68 _et seq._--_Leidy_, ‘Proc. Acad. Phil.,’ viii, p.