JOHN HARRIS; SPALL ANZANI. I 2 i 



for them, that they may by the warmth of the sun be easily hatched into living 

 creatures .... and perhaps sometimes both these circumstances, and others of the 

 like nature, concur for their production." 



Making due allowances for John Harris's conception of Infusoria as the 

 product or offspring of microscopically minute insects, it is astonishino- to 

 find how closely his two suggestions of their being primarily attached in the 

 form of eggs to the rugse and plicae of the surfaces of the veo-etable sub- 

 stances experimented on, or of their falling from the atmosphere and 

 germinating in such suitable liquid nidus as may present itself, coincide 

 with the actual distribution of infusorial eggs or spores as demonstrated by 

 the most recent research. 



Proceeding to an enumeration of the results obtained by the many 

 " ingenious and inquisitive men " who, following the recommendation of 

 John Harris, did " imploy their thoughts " upon the subject of infusorial 

 propagation, it has to be further recorded of Spallanzani that he initiated 

 the experiment of filling flasks with organic infusions, and after hermeti- 

 cally sealing their apertures and boiling their contents, showed that no 

 life was generated in them, however long they remained in their closed 

 condition. The Genevan naturalist Bonnet, the intimate friend of Spal- 

 lanzani, adopting the same line of argument, proceeded so much further as 

 to declare that all substances both organic and inorganic were permeated 

 with these infinitely minute germs, and that these germs were in some cases 

 able to resist the highest temperatures. This latter property ascribed to 

 the organic germs was the outcome of certain exceptional cases in which, 

 in infusions boiled and confined in flasks in the manner above indicated 

 living organisms were found both by himself and Spallanzani to make 

 their appearance. 



This point of the controversy being arrived at, the subject attracted 

 such general attention that the whole world of science may be said to have 

 divided itself into two hostile camps, the one supporting Needham's and 

 Buffon's, and the other Spallanzani's and Bonnet's hypotheses. As 

 rallying titles or nonis de guerre that should serve to distinguish the 

 adherents of these two respective camps, that of " heterogenists " was 

 generally associated with the supporters of abiogenesis, or who, as the 

 word implies, advocated the heterogenetic or spontaneous generation of 

 the organisms under dispute ; that of " panspermists " being applied with 

 corresponding significance to those followers of Spallanzani who attri- 

 buted the rapid propagation and distribution of Infusoria to the universal 

 presence of their germs in the surrounding air. Among the many doughty 

 champions who, as successors to Needham, distinguished themselves for 

 their ardent devotion to the cause of abiogenesis or heterogeny during 

 the earlier portion of the nineteenth century, have more especially to be 

 placed on record the names of Lamarck, Oken, Bory de St. Vincent, and 

 Dujardin. On the side of the " panspermists," on the other hand, appear 

 during the same epoch those of Paul Gervais, Schwann, Schultze, and 



