78 THE MICROSCOPE. 



her of forms under which a single germ may 

 develop itself." * 



Professor Carpenter elsewhere pursues a simi- 

 lar course of argument in reference to the Infu- 

 soria : " When we consider the extraordinary 

 rapidity of the multiplication of these animal- 

 cules, and the fact that a succession of different 

 forms may be presented by one and the same 

 being, the difficulty of accounting for the uni- 

 versality of their diffusion, which has led some 

 naturalists to believe in their ' spontaneous ge- 

 neration/ and others to regard them as isolated 

 particles of higher organisms set free in their 

 decomposition, so as to constitute an equivocal 

 generation,' is as easily got over as we have 

 seen it to be in the case of the fungi/' 2 



7. At one period the Yeast-plant was adduced 

 as a striking example of the spontaneous pro- 

 duction of cellular substances. A few lines from 

 the pen of the late Professor James F. W. John- 

 ston scatter such fancies to the winds : " The 

 yeast with which we raise our bread is a minute 

 plant belonging to the division of the Confervce. 



1 Carpenter on the Microscope, p. 383. 



2 Ibid. p. 485. 



