'210 Dr. II. Charlton Bastian on (he. ITeterogenetic 



tlie tip of tlie snout. Skin of the tliroat and sides of the body 

 ^vith minute tubercles. lieddisli brown above, closely 

 marbled with darker brown^ tibia? with three dark cross-bars ; 

 pale beneath. 



From snout to vent 35 mm. 



Hah. Mount Saribaw, Samarahan River, Sarawak. 



This rather obscure little frog in general appearance 

 resembles small specimens of Rana Ku/ih'i, D. & B., but the 

 distinct tymjianum and expanded tips of the digits readily 

 serve to distinguish it from that species. The type and only 

 known specimen (a female) is deposited in the Sarawak 

 Museum. 



XXV. — The Heterogenetic Origin of Fungus-germs and 

 Mohads. By H. Charlton Bastian, M.A.-, M.L)., 

 F.KS., F.L.S. 



[Plates XIV. & XV.] 



Since my communication to ' Nature ' on this subject, on 

 Nov. 2-4: of last year, I have been devoting much of my 

 leisure time to further observations on the development and 

 transformations of small Zoogloea masses, with the result 

 that 1 have abundantly confirmed the truth of my original 

 observations, and have also been able to fill up several gaps 

 in my previous knowledge. I have satisfied myself also tliat 

 by far the best way for readily investigating these phenomena 

 is to obtain very thin bacterial scums, by using filtered in- 

 fusions not too strong, and a depth of fluid of rather less than 

 one inch. As all the processes that I have been describiiig 

 go on in the dark quite as well as in the light, the simplest 

 plan is to filter the infusion, prepared as previously directed *, 

 into small one-ounce earthenware pots, over which the covers 

 are then placed till the time comes for the examination of 

 their contents. If three or four pots are prepared at the 

 same time, they may be opened at will on successive days, 

 or some may be exposed to one toni])erature and some to 

 another. 



It is important to bear in mind two fairly distinct aspects 

 of my observations, corresponding with different stages in the 

 processes described. We have to. do (1) with the growth, 

 the individualization, and the processes of segmentation taking- 

 place in masses of Zoogloea. We have also to do (2) with 

 * * Nature/ Nov. 24, 1904, p. 77. 



I 



