( 404 ) 



for the fiirtlior experiments on li(|iii(l meilia as the cnido culliwes, 

 of A\ liicli many experimeiils, coiiliiuied tor years. ha\e conxiiiecd us. 

 E\ery ihoiiuiil of symbiotic i-elalioiis on w liieli the cai'hon assimilation 

 by our bacterinm miuht I'c^pose is tlici-eby e.\ebi(l(Ml. so that at least 

 the I>ioh»,i>ictil si(h' of this part of our problem is clear. 



('oncei'jiinii' the furthci' pro|)erties of our Itacterinm in piu-e cnltin-cs, 

 we cnii be In-ief. in the films, as well as on in the colonies on the 

 solid media, it consists of minute, thin and short rodlets, ])roitubly 

 always immobile. They ai'c ca. 0.5»/ wi(l(> and 0.5— 4 ƒ( loniii'. The 

 lenji'th however is \ery \ariablc and fre(|uently pai'ticles are seen 

 0.5 ft wide and 0.7 — 1 ;/ lonu'. Often. ^^ hen not nsinu' reajients, such 

 as (hein^" substances oi- acids, no structure at all is to be obserxcd, 

 neither in the colonies nor in the tlowinu' pellicle, but the bacteria 

 at once become visible by staininu' the preparations. The thick cell- 

 walls foi'ui the chief constituent of tiie colonies; albuminous nialtei" 

 is only present in a slii>lit (piantily in this bacterinm. 



4. T\[V. MTR1ÏI0.N WITH AT.MOsrill'.RIC ( ARIiU.N. 



A Li'ood appreciation of the carbon accumulation may be had as 

 well b\ a direct wciuhinu' as i»y the permaniiajiate method. 



For both determinations it is possible, to su(d< oil' the fluid, w liich 

 is practically free from bacteria, wholly or pai'tly b-om beneath the 

 lilm, so that the (|uaiitilv of the culture material, destiiied foi- the 

 filtration or the detei-niination of the pernian,Lianat(> number, is not 

 too \-obnninou>. 



In our experiments there only resulted a precipitate of calcinni- 

 phosphate oi- calciumcarbonate, when we had used our tap-watei-, 

 which is rich in lime, and when kaliumphosphate to excess had 

 been added. These precipitates can, however, i)e dissolved bcjieatli 

 as well as in the lilm by dilute acid, and then the acid can be 

 expelled by further washinu'. The lilm is so <lry ami \vetled \\[\\\ 

 so much ilifliculty. that all these manipulaticuis may be eifected 

 without much loss of material. 



The permang'anare number was determined after Klbki/s M niethod. 



In relation to the ([uaJitity of organic mailer found by direct 

 weig'hinu' oi* by the })erman,uanate method and formed from the 

 atmos|>heric carbon, the following" should be well observed. 



x\s />. oruiocarhopliilus grows only on I he free snrfacc of the 



1) TiEM-\N.\-G;\KTXEu's Haiitlbucli (ler Untersudiun^' der Wasser, 4e Autl. pag. :2bo 

 1895. 



