120 SPONTANEOUS GENERATION. 



subsequent publications, declared that infusorial animalcules were directly 

 and spontaneously engendered from more highly organized bodies in a state 

 of putrefaction. This bold declaration was entirely approved by Bufifon, 

 who further maintained that with respect to these organisms such a mode 

 of generation was not only the most frequent and universal, but also in all 

 probability the most ancient. 



Such being the definite position taken up by the advocates of spon- 

 taneous generation, it was not long before it was vigorously assailed, the 

 controversy that ensued surpassing probably in acrimony and the extent 

 of its duration that of any yet brought within the area of scientific polemics. 

 The earliest authority to declare himself opposed to this doctrine and to 

 submit an intelligible interpretation of the apparently anomalous conditions 

 of growth and reproduction of infusorial organisms, is usually held to be 

 the Abbe Lazzaro Spallanzani, of Pavia, who in the year 1765 enun- 

 ciated the opinion that such animalcules were propagated through the 

 medium of minute germs constantly present in the atmosphere, and 

 which fructified or developed immediately they came in contact with 

 the conditions suitable for their growth furnished by artificial or other 

 infusions. The atmospheric " germ theory," attributed to Spallanzani, can 

 boast, however, of a far more remote antiquity. Seventy years prior to 

 the time of Spallanzani (1696), an Englishman, John Harris, whose name 

 as one of the earliest observers of infusorial life has been previously 

 quoted, contributed to the ' Philosophical Transactions ' a suggestion con- 

 cerning the generation of these minute beings that is now, almost two 

 centuries later, found to represent the true position of the case more nearly 

 than any of the manifold interpretations brought forward between that date 

 and the present time. In the course of his observations upon the subject 

 of infusorial animalcules, embodied in the foregoing communication, the 

 following paragraph occurs : — 



" How such vast numbers of animals can be as it were at pleasure, produced, 

 without having recourse to equivocal generation, seems a very great difficulty to 

 account for. But the solving of it that way makes short work of the matter (for 

 'tis easie enough to say they are bred there by putrefaction), yet the asserting 

 equivocal generation seems to me to imply more absurdities and difficulties than 

 perhaps may appear at first sight. I wish therefore that this matter would a while 

 imploy the thought of some ingenious and inquisitive man. In the mean time I've 

 conjectured that these animalada may be produced by one or both of the following 

 ways. I. I have thought that the eggs of some exceeding small insects, which are 

 very numerous, may have been laid or lodged in the plicre or rugae of the coats of 

 the grain by some kinds that inhabit the same as their proper places. For that 

 insects of the larger kinds do frequently thus deposite their eggs on the flowers and 

 leaves of plants, has been often experimented ; and 'tis very probable that the smaller 

 or microscopical insects do the same. Now these being washed out of the seeds, by 

 their immersion in water, may rise to the surface and there be hatched into those 

 animals which we see so plentifully to abound there. II. Or the surface of the 

 water may arrest the straggling eggs of some microscopical insects that were perhaps 

 about in the air, and being fitted and prepared for the purpose, by the infusion of 

 proper grain, or a i)roportionable degree of heat, may compose so proper a nidus 



