December 24, 19H] 



NATURE 



4o 



vacuole near the posterior extremity, rhythitiically 

 ^penSg, and sharply closing about every twenty | 



''Fla^ella nuclei, and contracting vacuoles appearinR ' 

 in n!na units independently of heredity and as 

 dTivativ? from chance bacterial aggregates, such 

 He s no V revealed suppK us with marvels far sur- 

 pa^s^^ng hat was previously seen in the way of ongm 

 C? nucfei and free-Jell fornnation durmg the genesis o 

 brown Fungus-germs-though even these latter 

 changes give^the^ death-blow to Virchow's celebrated 

 dictum, omnis ceUtila e cellula. 



Couversion of lltimate Segments of Zooglocas inio 



Amoebae. 



This is perhaps a more interesting and remarkable 



transformation than either of the other txxo. When 



nast wrote on this subject I was altogetner unaware 



of the nature of the differential conditions favouring 



the conversion into Amoeba rather than into Mon^d^ 



Now I have found that this production of Amoebae 



can almost alwavs be brought about by preparing the 



nfusion at a temperature of 85°, rather than at 



^or^llv to be seen in embryo Fungus-germs just 

 treneraliv 10 ue s^cw . tu,. i-ittor are also 



""T^ of .he .mriads of An,a,b3. as f^l'T'^^ 



- ..'-r'i" or'r:»q'i:u;a A co„ 



^^X'H?;SS?;/LTe^"^l' ru ,^ 'if ;nuc>« of 



p,(;. 6 —A and BX500; CX700. 



c,o° F and bv subsequently keeping the pots at a 

 impe^kt^re rather higher than that general 

 •idooted. Sometimes, however, in such tr.al^ botn 

 MoTds and Amoeba are produced -"-'^-"/^-'>-„. 

 The procedure mentioned generally leads to the pro 

 auction of a verv large number of Zooglceas, which 

 h"ve essent?allv the same bacterial constitution and 

 mode of segmentation as have been met -jth m the 

 ZhTr Zooelceas, and which are represented in Fig. 2. 

 "X tran "on;ed ultimate products of segmentation 

 beiin as in the last case, to show themselv_es on or 

 ^bout'the third dav, while by the fourth and fifth da^. 

 "ctual mvriads of minute Amoebae are to be seen m 

 eve^ Portion of the scum taken up for examina ion 

 'o that at last no traces of the very numerous Zooglceas 

 from x4ich thev have been derived are to be ound. 

 ¥rse VmibL often at first have a single flageiluni^ 



One of the fin^l stages in such a resolution is shown 

 InFiff- \ wheretheultimateumts, which are mixed 

 with a' few actual Amoebae, are still pretty closely 

 aeieSated In a few of them quite small nuclei are 

 sK though these are much smaller than what are 



XO. 2.^56, VOL. Qd.1 



Fig. 7.— xsoo. 



bv the latest workers on these organisms, namely, 

 T' W Cropper and A. H. Drew, in their recently 

 iublished 'Researches into Induced Cell-Reproduction 

 in Amoeba." The rapid appearance therefore show^ 

 to occur of mvriads of minute Amoebae would be quite 

 inexplicable bv ordinary- processes. 



In what has been said details have been given which 

 wil almost certainly lead, at will, to the production 

 either of Fungus-germs, of Monads, or o^ Am^b^. I 

 have alreadv expressed the opinion (p. 462) that \se 

 have not necessarily to do with different bacteria in 

 these cases, but rather with the same bacteria differ- 

 entlv modified bv the prolonged, though comparatively 

 slight, differences of temperature maintained during 

 the production of the infusions. 



The recent access of cold weather has enabled me 

 i to confirm this, and has. moreover, shown that the 

 I temperature at which the pots are kept is only a little 

 ' less important than the variations in temperature at 



