LINNEAN SOCIETY OF LONDON, XXVU 



rate apparatus are performed without any special instruments 

 whatever ; yet we learn, from an equally strong passage in a subse- 

 quent page, that these creatures do perform aU the functions which 

 constitute in their aggregate the life-history of an animal; and, 

 without strong evidence to the contrary, we have no right to con- 

 clude that this vital power is the result of those purely physical forces 

 which produce crystallization, and is not transmitted from an orga- 

 nized being similar to themselves. It is to be regretted also that 

 the anonymous reviewer should have adopted a tone so depreciatory 

 of a work evincing such elaborate and extensive research, such 

 powers of methodizing, and lucidity of exposition. Still less does it 

 seem consistent with that impartiality which every reviewer is sup- 

 posed to possess, that, when returning to the subject in the Athe- 

 naeum of April 25, he should have cited as conclusive in favour of 

 spontaneous generation, the authority of Pouchet, Joly, Musset, 

 Schaaifhausen, Mantegazza, and "Wyman, completely ignoring the 

 refutation of Pasteur, considered so satisfactory by the French Aca- 

 demicians. 



Propagation by division, in plants and in some of the lower 

 animals, is too patent to the senses of the most casual observer to 

 require special notice ; in many plants, indeed, especially in moist, 

 cool climates Httle favoui-able for the ripening of seeds, it seems to 

 be almost the only mode adopted by nature, acting sometimes with 

 extraordinary rapidity and at great distances, as in the case of the 

 Elodea canadensis, which so suddenly choked up our water-channels 

 in 1847 and 1848, The chief question connected with it is, how far 

 it supplements or takes the place of generation ; whether it can 

 be carried on indefinitely, or whether the i-ace thus formed ulti- 

 mately dies out — once a favourite theory among gardeners, but now, 

 I believe, generally abandoned, and I am not aware of any recent dis- 

 cussion on the subject. Agamic generation has, however, much occu- 

 pied the attention of naturalists in both its aspects — that of genera- 

 tion by spores or germs in those lower orders of plants and animals 

 where no sexual organs have been detected, and parthenogenesis, 

 where such ova or germs of the female as ordinarily require fertili- 

 zation by the male are developed into perfect beings without that aid. 



The limits of reproduction by agamic spores have been gradually 

 restricted to the very lowest forms of organization in both kingdoms ; 

 and even there analogy has led to the suspicion that sexual organs 

 do exist, although as yet inappreciable by our means of observation. 

 Among the most important recent researches under this head in the 

 animal kingdom are those of M. Balbiani on the sexual phenomena 



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