DIFFICULTIES. 27 



DIFFICULTIES. 



From that time to the present the controversy has been 

 unceasing. Those who believed that the vital theory was 

 true still maintained it, for they had seen definite forms re- 

 produced in definite forms, by virtue of definite forms. They 

 returned to their microscopes and followed again the growth 

 of the yeast plant. They saw again the buds given off from 

 the cells, and reproduce other cells, like in every respect to 

 the mother cell; and these in turn reproduce other cells of 

 the same likeness; satisfying the basis as given by Prof. 

 Liebig. 



But the microscopes of that day were poor, trained ob- 

 servers were scarce, the subject was new, the modes of de- 

 monstration were comparatively clumsy, and in many respects 

 faulty. Under these difficulties progress was exceedingly 

 slow, at best; and for a time no substantial advance was 

 made. But gradually, as the number of the observers of it 

 increased, the yeast plant, as the active principle of yeast, and 

 upon which its action was dependent, was accepted by a large 

 proportion of the learned men of the world. It is, however, 

 a noteworthy fact that many of those who accepted this re- 

 fused to accept the vital principle for the other fermentations; 

 which would seem naturally to follow. This refusal seems to 

 have found a basis in certain arguments brought forward by 

 Prof. Liebig, especially such as the following : If oxamide be 

 brought in contact with oxalic acid dissolved in water, the 

 following changes take place : the oxamide is decomposed by 

 the oxalic acid, provided the necessary conditions for their 

 exercising an action on each other be present. Although the 

 oxamide is not at all soluble, the elements of water unite 

 with it, and ammonia- is one product formed and oxalic acid 

 the other, both in the proportions to form a neutral salt. 

 Here the contact of the oxamide and the oxalic acid induces 



