The Theories of Cell Development. 
125 
views of Schleiden, we come to that phase of spontaneity which, if 
established, fully demonstrates the possibility and indeed the 
constancy, of the spontaneous origin, not of individual cells alone, 
hut of living beings. 
It does not come within the limits or scope of the present 
article to review the history of the long, and as yet unsettled, 
contest concerning the spontaneous evolution of cells, or of those 
simple aggregations of cells which form the lowest types of living 
things. For a very complete review of this subject, I take great 
pleasure in referring to the essay by Professor J. C. Dalton, in the 
‘ New York Medical Journal’ for February, 1872. The doctrine 
of spontaneous generation was generally believed in by the ancients ; 
was disproved, in all except certain “ exceptional ” cases, by Begnier 
de Graaf (1672) and Yon Baer (1827); was revived by Needham 
(1748), and again controverted by Spallanzani (1775) ; was 
vigorously assailed by Schultze and Schwann (1836 and 1837), 
and for twenty years after the period last mentioned was generally 
abandoned by scientists as untenable. “ The production of living 
beings without parents was a theory admitted to have no reasonable 
basis for its support, and was regarded simply as a curious relic of 
antiquity.” * 
But in the year 1858 the doctrine of spontaneous evolution was 
revived by Pouchet, of France, as a sort of buttress to support the 
conclusions to which he was forced by the revelations of modern 
geology. Pasteur, however, and several other members of the 
French Academy, repeated Pouchet’s experiments with entirely 
negative results, and again this troublesome ghost seemed upon the 
point of being laid, when Professor H. Charlton Bastian published 
liis series of experiments, and announced himself as “ content ” and 
“justified ” in “believing that living things may and do arise de 
novo.” According to Bastian, various unicellular organisms are 
pretty constantly developed in boiled and hermetically-sealed in- 
fusions of hay, turnip, &c., and also in certain saline solutions 
treated in like manner. The reader is referred to Dr. Bastian’s 
work, the £ Beginnings of Life,’ recently published, for an extended 
account of his very interesting experiments, and the accompanying 
illustrative figures. He claims to have demonstrated that monads, 
bacteria, torulse, vibrios, leptothrix filaments, fungus spores, and 
various unclassified organisms of cellular structure, are developed 
from solutions of organic and saline substances absolutely destitute 
of living germs ; hence they must originate de novo. This, of 
course, is the very essence of free cell development, or rather it is 
something more than that, since it confers upon any solution of 
organic or saline matters containing the chemical elements of proto- 
plasm, the power not only to generate cells, but to spur them 
* Dalton, foe. cit. 
