690 Journal of Agricultural Research voi.vi.No.is 



(I), and the occurrence of gonidia budding out of the normal cells (K) 

 have been observed in every case. With all those cultures which regu- 

 larly produce endospores (No. 31-34, 41, 42), large cells belonging to 

 types A, B, C, and L were observed; and they were not observed with 

 the same constancy in cultures 35-40, 43-48. Of all these organisms 

 none are known to produce endospores. Bad. bulgaricum (No. 49), too, 

 is spore-free; but closely related forms isolated from the stomach have 

 been reported as producing endospores. The formation of cells of type 

 B, C, and L makes it highly probable that an experimental trial to 

 induce spore formation may soon be successful. However, the same 

 possibility is by no means excluded in the other cases. It may be that 

 small spore-forming forms can be branched 1 off from the other cultures. 

 Indeed, we have already obtained some quite encouraging results in this 

 line. Whether, then, another progression to the large cell types will be 

 possible is entirely an open question. 



Referring again to our introductory remarks, we take this opportunity 

 to point out specifically that these perhaps somewhat surprising state- 

 ments should by no means be considered merely as some absurd poly- 

 morphistic hypothesis. The well-known character of Bad. pneumoniae, 

 for example, will by itself remain completely unchanged, whatever may 

 be the result of further investigations upon the full life cycle of this 

 organism. If there is a spore-forming type, and perhaps even genetic 

 relations with some large-sized cells, this would in no way interfere 

 with nor impair the well-established facts already collected. Such wide 

 morphological differences must always be connected with no less con- 

 siderable alterations of the whole physiological character, so that these 

 other types, if they are known, of course, are stored away as entirely 

 different "species" in various remote places in the so-called "system" 

 of bacteria. This conclusion can be drawn with absolute certainty from 

 our observations on B. azotobacter as well as from Henri's experiments 

 (10) with B. anthracis. If only those changed forms, frequently seen 

 in all bacteriological laboratories, had not been persistently discarded as 

 uninteresting "involution forms" or as "contaminations," the whole 

 situation would undoubtedly be much clearer and much more satis- 

 factory. At present it is not our intention to dwell upon the numerous 

 details collected in our studies of the life cycles of the different organ- 

 isms. Though the broad types of growth are the same with all, the 

 morphological details, of course, differ considerably. Figures 25 to 30 

 (PI. E), 31 to 36 (PI. F), and 37 to 40 (PI. G) will furnish sufficient proof 

 in this direction, especially when compared with our illustrations of B. 

 azotobacter. It may suffice to add the following remarks: 



Figures 25 to 27 (PI. E) illustrate the appearance of the same cul- 

 tures of B. subtilis on a beef -agar slant, made from a 1 -day-old colony 

 on a beef -agar plate. The smear made directly from the colony showed 



