SOIL PROTOZOA. 319 



The posterioi' end is drawn out into a, long and exceedingly fine 

 tapering tail, and the contractile vacuole occurs just where the 

 body begins to narrow down. 



The tlagella are numerous and comparatively short. They 

 vary in number from seven to eighteen, and the smaller the 

 organism the fewer the liagella. They are situated in most cases 

 in two lateral rows towards the anterior end of the body, one 

 row being dorsally and the other ventrally placed. I have care- 

 fully noted the dis])Osition and number of the fiagella, and find 

 that they are not equalW distributed on either side, but exhibit 

 a considerable amount of variation in this respect. Klebs, on 

 his PI. xvi. fig. 9 c, shows a row of fiagella extending backwards 

 on one side as far as the beginning of the tail. I have not 

 found anything like this in my organisms. 



A few of the organisms were fixed just as they were twisting 

 spirally, and one of these is shown in fig. 48. It will be seen 

 from this that the edges of the body are curved, and that the 

 fiagella have their oi'igin close to the edges. Each fiagellum 

 arises from a small basal granule or blepharoplast distinctly seen 

 in the stained material. I cannot say whether there is a mouth, 

 and although I watched the creatures in life for a long time, I 

 never saw them take in food. There are numerous laige granular 

 bodies, howevei', in the cytoplasm in many of the forms which 

 appear to be ingested bacteria, and because of this, I am of 

 the opinion that a mouth is present. I believe it is situated 

 towards the anterior end, for I have made out, in some cases, a 

 somewhat lighter area here which might be considered as the 

 mouth. In the greater part of the body the cytoplasm is very 

 finely granular and evenly distributed, but towards the posterior 

 end, in the region of the contractile vacuole, it is frequently much 

 vacuolated. 



The nucleus is a very interesting structure. It is, in most 

 cases, of considerable length, and is situated about half-way 

 down the body. It consists of a long narrow rod of granular 

 material, frequently one -quarter to one-thii-d of the body in 

 length. Towards the middle of it is placed a circular karyosome 

 of deeply staining chromatin. The extra-kaiyosomic portion of 

 the nucleus appears to be very little diflierent from the general 

 cytoplasm in staining reactions, and is separated from the latter 

 on all sides by a very narrow clear space. There does not appear 

 to be any nuclear membrane. At all events, I have not made 

 out anything comparable with the nuclear membrane of other 

 flagellates and amoebse. From the appearance of the stained 

 examples, it seems that all the chromatin is concentrated in the 

 deeply staining karyosome, there being only small scattered 

 granules in the rest of the nucleus. 



The nearest approach to this nuclear apparatus which I have 

 been able to find, is that which occurs in certain Euglenoidea, 

 for example, in Euglena viridis (Keuten, '95), in which there 

 is a fairly large nucleus consisting of a central karyosome 



