SOIL PROTOZOA. 321 



B. Rhizopoda. 



Each of the soils yielded small amoeb?e of the Umax type, and 

 I have been fortunate in obtaining a number of stages in the 

 division of one or two of the forms. 



(1) Amgeba lawesiana, sp. n. (Pis. III., lY., figs. 49-65.) 



I propose this name * for a small amoeba which occurred in a 

 culture of Broad balk 1865 soil. I put up the culture in the 

 hope of obtaining another kind of protozoon, but instead of 

 getting this particular organism, I obtained an almost pure 

 culture of the amoeba in question. Unfortunately, I was unable 

 to devote much attention at the time to observing the living 

 organisms, and for this reason I am not able to state definitely 

 whether a contractile vacuole is present or not. The conditions 

 prevailing at the surface of the culture were very favourable to 

 active life, for my permanent pi'eparations show that the amoebae 

 were ingesting large numbers of bacteria and dividing forms are 

 fairly abundant. 



I have been fortunate in obtaining an almost complete series 

 of dividing organisms, and from the appearance presented by the 

 nucleus during these phases there can be no doubt that this 

 amoeba is very closely related to Amoaha glebce, which Dobell 

 ('14) has recently described in great detail. It is also similar in 

 its nuclear changes to Amceha lamellipodia (Glaser, '12), and the 

 large amoeba fi-om liver-abscesses, described by Listen and 

 Martin ('11), and also to ATnceba cacumis and Amoeba gobaimi- 

 ensis (Martin & Lewin, '14), 



Nevertheless, it differs from all these in certain important 

 details, which are dealt with later on, and for this reason I 

 propose to create a fresh species for its reception. 



It is rather smaller than Ainmba glebie., and the following are 

 some of its principal measurements : — 



Diameter of rounded forms 1 2-1 5 /x. 



Diameter of nucleus 4- 5 ^. 



Diameter of karyosome 2 /^ . 



Diameter of ripe cysts 10-11 /x,. 



(a) Structure. 



When in motion, the body becomes extended in the typical 

 Umax shape and presents a blunt advancing pseudopodium. The 

 protoplast is composed of an almost hyaline ectoplasm and a much 

 vacuolated endoplasm. In fig. 49 the alveoli of the endoplasm 

 are very irregular in shape and distribution, but in the almost 

 spherical forms assumed during nuclear division the alveoli are 

 fairly regulai'ly distributed throughout the endoplasm and are 

 more equal in size. The body is often crowded with ingested 



* I have named this amoeba after Sir John Lavves, the founder of the Rothamsted 

 Experiments. 



