TRIPYLA MONOHYSTERA 



199 



seem usually to gain entrance to the body at or near the caudal extremity, for 

 in almost all cases where their number 

 is few they are confined to the tail. 

 See Fig. 3. Thence they seem to work 

 their way forward, especially along the 

 lateral fields, so that finally they may oc- 

 cur throughout the length of the body 

 in hundreds of thousands. These ob- 

 jects are extremely minute and can be 

 satisfactorily examined only with the 

 aid of the highest powers of the micro- 

 scope. At first sight they appear to be 

 crescent shaped, a deception due to their 

 peculiar refractive properties. Careful 

 focusing shows that the greater portion 

 of the sphere, an eccentric portion, is 

 but slightly refractive. The remaining 



Fig. 3. Tripyla 

 This active, voraciov 



monohyslera. 

 s little nema 



is very common in filter-beds. 

 Often the remains of several other 

 nemas are to be found in its intes- 

 tine. The specimen figured had 

 been feeding on a variety of micro- 

 zoa. To be seen in the intestine 

 are a nema, nematod ing: the 

 "gizzard" of a rotifer, rot ing; and 

 a number of protozoa, ing. The 

 egg shown has just received one of 

 the syngonic sperm cells sp, and has 

 thrown off the first polar body, corp 

 plr I. The beginning of a sporo- 

 zopn (?) infestation is shown in the 

 tail, par. The renette of this nema 

 (ran; ex p) has hitherto remained 

 unknown. An organ of consider- 

 able size, but of unknown signifi- 

 cance, org ?, is also now for the first 

 time shown to exist in the neck. 

 For abbreviations see p. 212. 



mini/nil IIHJ 

 niin inl 

 nclint 

 nclint 

 dint 

 ijniinlL 

 "iH I 

 ia 



portion is more easily seen, and, when 

 it comes into view in optical section, 

 presents the contour of a crescent; is 

 therefore in reality bowl- shaped. I have 

 made no serious attempt to classify these 

 objects and can only suggest that we 

 have here a new sporozoon. If so it 

 may be the cause of a serious disease of 

 the nematode; often 10 to 20 per cent 

 of the individuals appear to contain it. 

 In some collections it occurs in practi- ^ 

 cally every individual. *"* 



Nemativorous. Nematodes having a nd mt 

 plain oesophagus, such as Tripyla, ^ 

 Mononchus, and Monhystera, often ex- 

 hibit a marvelous capacity for swallow- 

 ing relatively large objects. Some spe- 

 cies of Monhystera are able to swallow diatoms one-half to two-thirds as wide as 

 themselves, and one-fifth to one-sixth as long. Tripyla monhystera is rather 



