56 BULLETIN : MUSEUM OF COMPAEATIVE ZOOLOGY. 



I have found several stages which I beheve lead up to this condition. 

 Apparently the substance which is destined to envelop the nucleus first 

 collects along the partition separating the body from the head of the 

 animal (Fig. 13). Possibly the formation of this thick envelope is pre- 

 paratory to the production of the spores. 



The posterior or body half of the animal is principally occupied by a 

 highly vacuolated protoplasmic mass (Fig. 7), which has usually reached 

 the state of a coarse reticulum. In this reticulum large pieces of wood 

 fibre and spores of fungi are frequently found embedded. This central 

 protoplasmic reticulum is completely surrounded by a granular proto- 

 plasmic wall {st.gran/. Figs. 7, 13, 15), which is continuous in front 

 with the granular pai'tition separating the " head " from the "body." 



The granular wall is not very thick, and passes on its inner surface 

 rather gradually into the protoplasmic network; but it is more sharply 

 defined on its outer surface, though even here the transition to a rather 

 thick cortical layer (st. ctx.. Figs. 7, 13, 15) immediately outside it is not 

 very abrupt. This cortical layer is composed of finely granular almost 

 homogeneous protoplasm, and is of nearh-, though not quite, uniform 

 thickness. Its average thickness is about the same as that of the inner 

 layer enveloping the bell. 



The surface of the " body " appears to be traversed by nearly equidis- 

 tant lines, which have a slightly spiral — left-handed or Iseotropic — 

 course (Plate 1, Figs. 1, 2). These lines appear to be continuous in 

 direction with the innermost set of cilia, which cross one another at the 

 posterior tip of the body, and in fact the lines are in my opinion due exclu- 

 sively to the presence of these cilia, which are closely applied to, but are 

 entirely free from, the wall of the " body." Frenzel's description of the 

 condition in Leidyonella is certainly not applicable here. Frenzel ('85, 

 pp. 306, 307) maintains that in Leidyonella the rigid cilia arise at or near 

 the anterior end of the body, but that, instead of being free throughout 

 their whole length, they are fused with the peculiar cuticula which covers 

 the body, causing ridges, which have a slightly spiral course (he does 

 not say whether right or left, and his figures are noncommittal), and 

 that they become free only as they project beyond the posterior ex- 

 tremity of the body. These ridges are stated to be much more promi- 

 nent in the anterior than in the posterior part of their course. But, 

 whatever may be the condition in Leidyonella, the spiral markings in 

 Trichonympha are not traceable forward any further than the boundary 

 between " body " and " bell," and they are not due to confluence of cilia 

 with the wall of the body of the parasite. 



