692 Journal of Agricultural Research vol. vi, no. 18 



The formation of the syinplasm in an 11 -day-old ammonium-citrate- 

 glycerin solution of B. fluorescens is shown in figure 30 (PI. E). This 

 figure should be compared with figure 11 (PI. B), showing the formation 

 of stained symplasm of B. azoiobacter. The dark rods also visible in 

 the former figure are of the H type. 



In figure 31 (PI. F) cells of Sarcina flava from a 1 -day-old beef -agar 

 slant are reproduced partially disintegrating into the symplastic stage. 

 The small symplasm in the center has already entered the formation of 

 regenerative units. Many of the cells are in the conjunct stage. 



Figure 32 (PI. F) illustrates the transformation of the symplasm of 

 Streptococcus lactis into man)? normal forms and some round regenerative 

 bodies, as observed in a 5-day-old peptone-lactose solution. As far as 

 this transformation has already taken place, it is clearly discernible that 

 indeed, as mentioned before, the whole material is used again for the repro- 

 duction of new cells practically without leaving any remnants. Figure 

 33 (PI. F) shows another "flake" of symplasm of Streptococcus lactis from 

 a 3-day-old milk culture containing many regenerative units and some 

 globular regenerative bodies. This illustration is of special interest for 

 the following reasons: Such globular bodies of different diameters are 

 produced by all kinds of bacteria (cf. fig. 13 of PI. C; fig. 25, 26, 27 of 

 PI. E). If they are dispersed in their symplasm and this is embedded 

 in the equally deeply stained casein of the milk, it looks nearly as if the 

 albuminous substances of the milk were forming granules which later 

 produce normal bacteria by germinating or stretching. The center of 

 figure 33 (PI. F), where a rather compact symplasm is lying above a very 

 thin film of casein, shows that these things are entirely separate and dif- 

 ferent. However, in the lower left part of the field some symplasm is 

 embedded in a thicker layer of casein, and here the situation is much 

 less clear. Now, Fokker (5), one of the few authors who are still fighting 

 in favor of spontaneous generation, has repeatedly pointed out that his 

 standpoint is strongly supported by the fact that the albuminous sub- 

 stances in animal tissues, as well as in milk and in blood, produce small 

 granules which later develop into normal bacteria. The assumption that 

 his subtrates were not sterile, of course, does not furnish a complete 

 explanation of these peculiar observations. We believe, however, that 

 our discovery of the symplasm and of its regenerative units settles this 

 question. 



That the formation of the symplasm and the regeneration of new cells 

 are by no means an abnormal occurrence merely caused by the unnatural 

 conditions under which our cultures are compelled to live in the labora- 

 tories can be deduced without great difficulty from different facts already 

 mentioned. However, we thought it useful to add to the illustration of 

 the milk culture another one reproducing an entirely "natural" occur- 

 rence. Figure 34 (PI. F) was taken from a smear made directly from the 

 content of a root nodule of red clover. The irregular, frequently branched 



