MORPHOLOGIC VARIATION OF BACTERIA 3 



rent views as to its etiology, was led to make some filtration ex- 

 periments, and found that from filtered urine, blood, and cere- 

 brospinal fluid from cases of meningitis, there could be cultivated 

 a pleomorphic organism appearing as large and small rods and 

 cocci (1915). He concluded that the meningococcus is but a late 

 non-virulent stage in the life cycle of £in organism which has a 

 filterable, virulent phase. Microscopic observation of cultures of 

 meningococci revealed great variation in size and the forma- 

 tion of small cells from larger ones by budding, also refractile 

 globular structures were found forming within some of the 

 larger cells which he says are ascospores. He therefore considers the 

 meningococcus to be a pleomorphic fungus belonging to the ascomy- 

 cetes (1917a). Multiple lateral and terminal buds were also found 

 to develop on typhoid and dysentery bacilli grown in acid media 

 (1917b), and these were observed to give rise again to normal rod 

 forms (1920). 



Lohnis (1916) observed a great variety of cell forms in cul- 

 tures of Azotobacter, and particularly the occurrence of slender, 

 spore-forming rods, from which he concluded that the normal 

 morphology of this organism is but a stage in the life cycle of a 

 spore forming bacillus. Further study of this organism led to the 

 conception of a complex cycle which was extended to apply to all 

 bacteria by observations of some forty-two other species. Later 

 (1921) appeared a very comprehensive monograph, which in spite 

 of its bias is an extremely valuable review of the literature, in which 

 he showed that the structures described by him had been repeatedly 

 observed, described, and illustrated by many of the previous bac- 

 teriologists, among them the most orthodox. 



Lohnis' hypothesis is so complicated that it cannot be readily sum- 

 marized. A few quotations may serve to outline its general scope. 



Contrary to the monomorphistic theory which only knows one constant 

 type of vegetative cell for every species, and not more than one type of repro- 

 ductive organ, the endospore, for merely one group of bacter'a, it has been 

 ascertained by numerous independent investigations that in reality all bacteria 

 are not only distinctly pleomorphous in their vegetative growth, but are also 

 able to produce various organs of reproduction. These are : Gonidia, regenerative 

 bodies, exo- and endospores, arthrospores, and microcysts. All of them are made 

 up of nuclear substances, which are reinforced by smaller or larger amounts of 



