284 Profs. Percy Frankland and Marshall Ward. 



mycete, has been the tracing of the successive stages of development 

 of the spores under high-power objectives; and here again I have 

 had the satisfaction of tracing the whole process in one of the fila- 

 ments of the same series as those figured in figs. 9, 13, and 14. 



The strand drawn in fig. 14 i, was left at 5.30 P.M. at a stage too 

 complex to follow further, and when its age reckoned from the swel- 

 ling of the spore which produced the filaments was 30^ hours. 

 At 9 o'clock next morning these filaments showed evidence of pro- 

 ceeding . to the development of spores, and before night every fila- 

 ment had a completely developed spore in each of its numerous 

 segments, or if any of the segments remained barren they must have 

 been very few indeed. 



I had already traced the development of the spores, but it was 

 obviously an interesting task to do this in one of these filaments which 

 I had kept so continuously under observation, and the following 

 description refers to a portion developed during the night from the 

 further growth of one of the loose filaments in fig. 14 i. 



To do this I exchanged the objective (E, occ. 4) for a l/12th oil 

 immersion, and at 10.30 A.M, made the notes of the first changes 

 which initiate the formation of the endogenous spores. This culture 

 which, as we have seen, was in broth at 20 C.* (occasionally lower), 

 was now aged 47^ hours from the moment of drawing the spores 

 (fig. 9 a). 



The first indication of spore-formation consists in the appearance 

 of brilliant points in the cells which have now ceased to grow or 

 divide. There may be one or two or more of these bright spots in 

 each cell, and the septa show signs which seem to precede a tendency 

 to split. They look swollen and bright, but I am not sure whether 

 this is really due to such a change in them, or whether it is owing 

 to a slight contraction of the protoplasm from contact with the 

 walls. 



During the course of the next three or four hours the bright, oily- 

 looking globulesf gradually enlarge, and, where more than one occur 

 in a cell, some may run together into one bright mass, which slowly 

 balls itself together in the centre of the cell, and, in the case described, 

 there was one such mass definitely established as an oval body in each 

 segment at 3.30 P.M. In the course of the next hour this bright, oval 

 body had increased in size, apparently at the expense of the cell- 

 protoplasm in which it lay, and constituted a definite spore. This 

 slowly acquired a more and more pronounced spore-membrane towards 



* This, like all the temperatures in this part of the work, refers to the air 

 temperature : a point of some importance later on. 



f They are not oil, because they stain with methylene blue and other dyes ; it is 

 more likely that they are the chromatin granules referred to in Hueppe, ' Methoden 

 der Bakt.-forsch.,' 5th edit., 1891, p. 154. 





