lxxiv report — 1877. 



During tho last seven or eight years, however, renewed investigations hy 

 most competent inquirers have followed one another in quick succession, from 

 a review of which we cannot but arrive at a conclusion adverse to the theory 

 of Hetorogenesis, namely, that no development of organisms, even of the 

 most simple kind, in fermenting or putrefying solutions, has been satisfac- 

 torily observed to occur when the conditions of the experiments were such 

 as entirely to exclude tho possibility of their being descended from germs, 

 or equivalent formative particles, belonging to preexisting bodies of a similar 

 kind. I can do no more here than name the authors of the most conclusive 

 experiments on this subject, nearly in the order of their publication, as those 

 of Mr. "W. N. Hartley in 1872, Messrs. Pode and Ray Lankester in 1873, Dr. 

 Burdon Sanderson in that and tho following years, Dr. W. Roberts in 1874, 

 Professor Lister in 1875, and most recontly of Professor Tyndall, Professor 

 Cohn, and of Messrs. Dallingor and Drysdale *. 



But, admitting that the evidence from direct experiment is such as entirely 

 to shut us out from entertaining the view that spontaneous generation 

 occurs in the present condition of the earth, we are not relieved from the 

 difficulty of explaining how living organisms or their germs first made 

 their appearance, nor are we debarred from attempting to form hypo- 

 theses as to how this may have taken place. First, upon the theory of 

 Evolution, which, strictly carried out, supposes the more complex organisms 

 to be derived from the more simple, it might be held that the conditions 

 affecting the combination of the primary elements of matter into organic 

 forms may at one time have been different from those which now prevail, and 

 that, under those different conditions, abiogenesis may have been possible, 

 and may have operated to lay the foundations of organic life in the simpler 

 forms in which it at first appeared — a state of things, however, which can 



* I may refer to Dr. Bastian's paper in ' Nature ' of June 30, 1870, and to his two 

 works, ' The Origin of the Lowest Organisms' and 'The Beginnings of Life,' and papers 

 to Boy. Soc. 1873. Mr. Hartley's researches, which were commenced in 1865, are described 

 in a paper printed in the Brocecdings of the Eoyal Society for 1872, and in his ' Lectures 

 on Air,' 2nd edition, 1876, where an interesting account of the whole subject will be found. 

 The experiments of Mr. Bode, of Oxford, and Brofessor Ray Lankester are described in 

 a paper on the " Development of Bacteria in Organic Infusions," in the Eoy. Soc. Broc. 

 1873, vol. xxi. p. 34:9. Dr. Burdon Sanderson's researches are contained in the Reports of tho 

 Medical Officer of the Brivy Council, and in various papers in ' Nature ' ; Dr. W. Roberts's 

 paper is printed in the Transactions of the Royal Society for 1874, vol. clxiv. p. 457. Bro- 

 fessor Lister's " Contribution to tho Germ Theory of Butrefaction and other Fermentative 

 Changes," &c. is contained in the Transactions of the Royal Society of Edinburgh for 1875, 

 p. 818, and is also given in ' Nature.' Brofessor Tyndall's researches are described in his 

 papers in the Broceedings of the Royal Society during the last two years. The work of 

 Brofessor Cohn, of Breslau, entitled ' Beitrage zur Biologie der Bflanzen,' 1873-76, contains 

 many memoirs bearing upon this subject, which have been partly published in abstract in 

 tho ' Microscopical Journal,' in which also will bo found, in a series of contributions extending 

 from 1873 to the present time, the interesting observations of Mr. W. H. Dallinger and 

 Dr, J, Drysdale. 



