Origin of Fungus-germs and Monads. 215 



inotionless spherical or ovoidal units, as shown in fig-. B, 

 which after a time become active flagLillate Monads. 



As I have indicated in my ' Studies in Heterogenesis/ 

 pp. 69-73, Monads are much more commonly produced from 

 the pellicle in another way — namely, as pale, diecrete, 

 motionless corpuscles more or less thickly distributed through 

 its under layers. These are to be seen often in the course of 

 the third or fourth day, when not a single active Monad has 

 hitherto been found. While if the same pellicle be examined 

 twelve or twenty-four hours later, the fluid may be discovered 

 to be swarming- with active Monads, all of about the same 

 size, and tliis size agreeing with that of the previously 

 motionless corpuscles. At other times swarms of minute 

 AmoebfB rather than of Monads suddenly make their appear- 

 ance where only motionless corpuscles M'ere previously present. 

 As the corpuscles sometimes develop into Monads and 

 sometimes into Amoeba?, I have been accustomed to speak of 

 them as " indifferent corpuscles.''^ Not unfrequently, how- 

 ever, after their formation they may remain for a much 

 longer time quiescent and without developing in either 

 direction. This was the case in a hay pellicle that I have 

 recently examined, in which such corpuscles were found in 

 enormous numbers and rather larger than usual. They were 

 first seen when a small pot containing same hay-infusion was 

 opened after four days, during which it had been exposed to 

 a temperature of 70° F. (21° C). The edge of a portion of 

 this pellicle is represented in fig. 7, A, while in B some of 

 the separate corpuscles are shown more highly magnified, so 

 as to reveal the nature of their contents. Nothing like a 

 nucleus is to be seen, nor can one be detected by the use of 

 any of the ordinary stains even when the corpuscles have 

 been allowed to soak in them for many hours. Logwood, 

 carbo-fuchsine, gentian violet, and mastzellen stain have all 

 yielded negative results. Not a trace of a nucleus is to be 

 found, and the corpuscles seem to be mere individualized 

 portions of Zoogloea intermediate in size between the brown 

 units on the way to the production of Fungus-germs, which 

 are shown in fig. 2, E and F, and, like them, containing only 

 a few bacteria in their interior. I have examined such 

 corpuscles over and over again, and always with similar 

 results. If they do not speedily develop, a limiting membrane 

 is produced which enables their contents to resist staining, 

 and causes the corpuscles themselves to shrivel if they are 

 mounted in glycerine and water. When these corpuscles develop 

 quickly, whicli is the rule, they give rise, as I have said, more 

 or less suddenly to swarms either of Monads or of minute 



15* 



