12 INTRODUCTION. II. 



required ; what might have been the influence of a long-continued current of elec- 

 tricity, under the same circumstances, upon the mixtures ? 



The experiments of Crosse and Weekes, in the production of the so-called Acarus 

 Crossii, were performed under the least favorable circumstances to the origination 

 of life, and, although neither an Acarus nor a Homunculus has been created under 

 the inspection of man, yet ridicule or prejudice should not prevent us from making 

 every observation and experiment which can bear on the subject, in order that we 

 may say positively whether living beings do or do not originate from the inorganic 

 world under natural and still-existing conditions. 1 



To the present, we are totally unacquainted with the mode of the primitive origin 

 of living beings ! 



Each species once in existence, very generally, and probably universally, requires 

 two distinct elements, denominated sexual, for its perpetuation. 



The power of reproduction by segmentation, budding, or the production of 

 numerous successions of asexual fertile generations is, probably, in all cases limited ; 

 the species necessarily reverting to sexual admixture for its perpetuation. 



The statements of Horkel 2 and Schleiden, 3 and their followers, that true sexes 

 do not exist in the phanerogamia have been most amply refuted by the more careful 

 observations of Amici, 4 Hugo von Mohl, 5 Carl Miiller, 6 Hoffmeister, 7 Gasparini, 8 

 Tulasne, 9 and others. 



Sexual elements have also been detected in most of the cryptogamia, and, in a 

 little time, will probably be discovered in all. They have been observed in Ferns, 10 

 Mosses, 11 and Alga?, 12 but not yet among Fungi. 



Having thus taken a cursory glance at the laws of life in general, we have next 

 to consider those especially operating in the production of parasitic life. 



Within living beings, i. e. within their cavities or the parenchyma of the organs, 



I The experiments of Crosse and "Weekes appear to me exceedingly absurd; for, in the first case, how were 

 the carbon and nitrogen of the animal body to be derived by the play of a voltaic current upon a solution of 

 silicate of potassa? If they previously existed in the water, was it not quite as probable that the ova of 

 Acari were there also? Again, when the solution of ferrocyanide of potassium was made the womb of life 

 by the electrical current, why could not the embryology of the new being be observed ? An Acarus is a 

 highly complex animal, presenting a well-developed tegumentary, muscular, and nervous system, and a 

 digestive, respiratory, and generative apparatus. The gap between the inorganic world and the Acarus is 

 greater than that between the latter and man ! 



Monatsb. d. Berlin. Akad. 1836. 



' Archiv f. Naturges. 1837; Nova Acta C. L. C. Acad. Nat. Cur. vol. xix. 1839, p. 27; Grundziige 

 d. Wissenschaftliche Botanik. 



4 Giornale botanico Italiano, An. 2 ; Annales des Sciences Naturelles, Botanique, 1847, t. vii. p. 193. 



5 Botanisehe Zeitung, 1847; An. Sc. Nat., Bot, t. ix. 1848. 



6 Ibid ' Ibid, and t. xi. 1849. 

 8 Ibid. Ibid. t. xii. 1849. 



10 Tulasne, ibid. t. xi. p. 5; ibid. p. 114. 



II Schimper: llecherches Anatom. et Morpholog. sur Ics Mousses. Strasbourg, 1848. This author 

 says, page 55: " Maisje tiens le fait qucjamais une mousse ne parvient d la fructification quand el/e se 

 trouve hors de f influence des organes queje considere comma des organes malts." 



12 Thwaitcs, in Annals and Magazine of Natural History, 1847, vol. xx. p. 9; ibid. p. 343; ibid. 1848, 

 2d ser. vol. i. p. 161. 



