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THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



or, as I would rather name it, " development." 

 But before proceeding to discuss the subject of 

 development in the higher animals, it is right to 

 advert to the preliminary and often-debated ques- 

 tion, which naturally presents itself, viz. : Do all 

 living or organized beings, without exception, 

 spring from germs, or from any kind of organized 

 matter that has belonged to parents ? or may 

 there not be some, especially among the simpler 

 forms (with regard indeed to which alone there 

 has of late been any question), which are pro- 

 duced by the direct combination of their compo- 

 nent elements, in the way of the so-called spon- 

 taneous or equivocal generation, heterogenesis or 

 abiogenesis ? 



The importance of the right solution of this 

 problem is not confined merely to the discovery 

 of the mode of origin of the lowly organisms 

 which have been the more immediate object of 

 investigation by naturalists in recent times, but is 

 one of much wider significance, seeing that, if it 

 shall be satisfactorily proved or even rendered 

 probable that in the course of cosmical develop- 

 ment all the various kinds of plants and animals 

 have been gradually produced by evolution out 

 of preexisting simpler forms, and thus the whole 

 series of organized beings in Nature has been 

 shown to be one of hereditary connection and 

 derivation, then it would follow that the history 

 of the origin of the simplest organisms may be 

 the key to that of the first commencement of life 

 upon the earth's surface, and the explanation of 

 the relation in which the whole succeeding prog- 

 enies stand to their parental stocks. 



From the very lucid and masterly view of this 

 subject given by Prof. Huxley in his address to 

 the Association at Liverpool, so recently as in 

 1870, in which the conclusion he formed was 

 based very much on the exhaustive and admi- 

 rable researches of Pasteur, I might almost have 

 dispensed with making further reference to it 

 now, but for the very confident statements since 

 made by the supporters of the doctrine of abio- 

 genesis, among whom Dr. Bastian stands most 

 prominent in this country, and for the circum- 

 stance that the life-history of many of the lower 

 organisms was still imperfectly known. 



During the last seven or eight years, however, 

 renewed investigations by most competent in- 

 quirers have followed one another in quick suc- 

 cession, from a review of which we cannot but 

 arrive at a conclusion adverse to the theory of 

 heterogenesis, viz., that no development of or- 

 ganisms, even of the most simple kind, has been 

 satisfactorily observed to occur in circumstances 



which entirely excluded the possibility of their 

 being descended from germs, or equivalent forma- 

 tive particles, belonging to preexisting bodies of 

 a similar kind. I can do no more now than 

 name the authors of the most conclusive experi- 

 ments on this subject, which I do nearly in the 

 order of the publication of their researches, as 

 those of Mr. W. N. Hartley in 1872, Messrs. Pode 

 and Ray Lankester in 1873, Dr. Burdon-Sander- 

 son in that and the following years, Dr. W. Rob- 

 erts in 1874, Prof. Lister in 1875, and most re- 

 cently of Prof. Tyndall, Prof. Cohn, and of Messrs. 

 Dallinger and Drysdale. 1 



But, admitting that the evidence from direct 

 experiment is such as entirely to shut us out from 

 entertaining the view that spontaneous genera- 

 tion occurs in the present condition of the earth, 

 we are not relieved from the difficulty of explain- 

 ing how living organisms or their germs first 

 made their appearance ; nor are we debarred 

 from attempting to form hypotheses as to how 

 this may have taken place. First, upon the the- 

 ory of evolution, which, strictly carried out, sup- 

 poses the more complex organisms to be derived 

 from the more simple, it might be held that the 

 conditions affecting the combination of the pri- 

 mary elements of matter into organic forms may 

 at one time have been different from those which 

 now prevail ; and that, under those different con- 

 ditions, abiogenesis may have been possible, and 

 may have operated to lay the foundations of or. 



i I may refer to Dr. Bastian's paper in KaUire of June 

 SO, 1870, and to his two works, "The Origin of the Low- 

 est Organisms,"' and "The Beginnings of Life." Mr. 

 Hartley's researches, which were commenced in 1SC5, are 

 described in a paper printed in the " Proceedings" of the 

 Eoyal Society for 1S72, and in his " Lectures on Air," second 

 edition, 1S7G, where an interesting account of the whole 

 subject will be found. The experiments of Mr. Pode, of 

 Oxford, and Prof. Pay Lankester, are described in a paper 

 on the " Development of Bacteria in Organic Infusions " in 

 the Eoyal Society "Proceedings" for 1S73, p. 349. Dr. 

 Burdon-Sanderson's researches are contained in the re- 

 ports of the medical officer of the Privy Council, and in 

 various papers in Nature. Dr W. Roberts's paper is 

 printed in the "Transactions" of the Royal Society for 

 1n74, vol. clxiv., p. 457. Prof. Lister's " Contribution to the 

 Germ Theory of Putrefaction and other Fermentative 

 Changes," etc.. is contained in the "Transactions" of th e 

 Eoyal Society of Edinburgh for 1875, p. 313, and is also 

 given in Nature. Prof. Tyndall's researches are described 

 in his papers in the "Proceedings" of the Eoyal Society 

 during the last two years. The work of Prof. Cohn, of 

 Breslau, entitled " Beitriige zur Biologic der Pflanzen," 

 1873-76, contains many memoirs bearing upon this sub. 

 ject, which have been partly published in abstract in the 

 Microscopical Journal, in which also will be found, in a 

 series of contributions extending from 1873 to the present 

 time, the interesting observations of Mr. "W. II. Dallinger 

 and Dr. J. Drysdale. 



