1908-9. ] On » E ORIGIN OF LIFE ON THE GLOBE. 429 
has rightly received the name of mother since all things are begotten 
of it and many living creatures arise out of it, having been generated by 
the rains and the warm mists formed by the sun.”* 
From the time of Lucretius and till the nineteenth century the 
belief in the occurrence of spontaneous generation was almost universal 
and it was not an unnatural result of the observations which were made 
in an uncritical age. It was well known that when a quantity of tissue 
like beef-muscle is exposed to the free air and sunshine at summer tem- 
perature the larval forms of flies and other insects appear in it in a few 
days. The explanation of their appearance there was that they were 
spontaneously generated in the putrefying animal flesh. This explana- 
tion was everywhere excepted until Redi, in 1668, definitely showed 
that when meat is placed in a wide-mouth jar and the mouth covered 
with thin gauze so as to permit free entrance of air and warmth, but 
also so as to exclude flies, no larve made their appearance in the medium 
and thus the larve which ordinarily grew there were not due to any 
spontaneous generation but to the eggs deposited by flies. 
These observations of Redi were conclusive so far as they went and 
gradually the instances where spontaneous generation was supposed to 
occur became fewer the more the microscope was employed to study 
the occurrence and characters of forms of life known as animalcule. 
It was not, however, admitted on all hands that the minute organisms 
such as the microscope of the seventeenth and eighteenth century 
revealed to the investigator arose from pre-existing forms and this view 
was stoutly maintained by Needham and Buffon. Needham found that 
when he heated infusions of animal or vegetable material in carefully 
corked vessels to such a temperature as would destroy germs existing 
in the infusions, the latter kept for a few days at the temperature of the 
room were found to swarm with animalcule and therefore the latter 
must have arisen from matter which was not alive. This work was 
repeated by Buffon and Needham’s results were corroborated. 
It was, however, pointed out by Spallanzani that Needham’s and 
Buffon’s conclusion did not follow from their results. He found that if 
the infusions were heated for half an hour or more in glass vessels 
hermetically sealed by fusing their necks in the flame, no animalcule 
*“Linquitur ut merito maternum nomen adepta 
Terra sit, e terra quoniam sunt cuncta creata. 
Multaque nunc etiam exsistant animalia terris, 
Imbribus et calido solis concreta vapore.” 
—De Rerum Natura, Lib. V. 793-790. 
