November 24, 1904] 



NA TURE 



79 



become converted into Monads or altered in a more or less 

 irregular manner. I attempted to stain some of the masses 

 with a dilute solution of gentian violet. One of these, in 

 which segmentation is pretty complete, is shown in 

 B (X700), while the scattered products of another mass are 



shown in Fig. 5, A (xgoo), after they had been lightly 

 stained with Westphall's mastzellen fluid. In this 

 embryonic condition the future Monads are seen as spherical 

 nucleated cells, either single or in pairs. Some of the 





r emulsion (> 



o) ; C, A 



loped from Zoi^^gl'u-a iimssts in a hay infusion 

 stained with logwood, from an egg and water 

 rnoebeE originating in the scum from an egg and 



Monads which were found a few days later in a motionless, 

 resting condition, are shown in B (X700). 



On other occasions I had been a little more successful 

 in photographing Monads produced from Zoogloea areas in 

 a hay infusion. Thus Fig. 6, A (x 500), shows some such 



NO. 1830, VOL. 71] 



Monads, found on the third day, which had been developed 

 from discrete corpuscles, and which were rendered motion- 

 less by a very weak osmic acid solution. These discrete 

 corpuscles, as well as the motionless corpuscles derived from 

 tlie segmentation of Zooglcca masses, sometimes become 

 converted into Amcebas rather than into Monads. What 

 the conditions are that favour this particular change I have 





-'-^' " " ■■~' 



Fiti. 7. — A ZoogKca 



ndergoing change ( X 375). 



been unable to ascertain, though I know that in rare cases 

 swarms of minute Amoebae rather than Monads appear in 

 this way in hay infusions. The production of swarms of 

 minute Amcebas is, however, the rule in the pellicle that 

 forms on an emulsion made by pouring about eight ounces 

 of water on a teaspoonful of mi.xed white and yolk of egg. 

 Such Amoeba;, slightly stained with logwood, are shown in 

 Fig. 6, B (X200), talien from a pellicle on the seventeenth 

 day, while in C (X125) they are seen, as I believe, origin- 

 ating in another egg and water emulsion on the eighteenth 

 day, in the midst of irregular clumps of bacteria. These 

 aggregates of bacteria had been noticed for several days, 

 but when first observed not a single Amoeba had, up to this 

 time, been seen either in them or in the surrounding 



Fig. 8.— Portion of a Zooglo: 



; about to segment ( X 500). 



fluid. Then there were appearances as though changes 

 were taking place within the aggregates, followed in two 

 or three days by the presence of swarms of minute sluggish 

 Amoeba around, and issuing from, the bacterial aggregates, 

 as shown in the figure under a low magnification. 



In reference to the occurrence of these swarms of minute 

 Ainoebs, I may say that I have never seen one of them 

 multiply by fission, and certainly their vast numbers are 

 not to be accounted for in this way. I make these remarks 

 concerning Amcebse without pretending that what I have 

 here said in regard to them is quite conclusive, or in any 



