D. Keilin 
93 
(figb. 11, 12, 13, 14 and 1/), the chromatic body always lies in the posterior 
portion oi the ciliate, so that after the division, this body is inherited by the 
posterior individual, while the anterior is always devoid of it. This shows that 
the chromatic bodies of different specimens of Mdupdselld are in no way related 
to each other, but are formed independently in each ciliate, which possesses 
them. 
In spite of a great number of Mdupdsslld having been found to contain 
the chromatic body, I have not yet been able to trace its origin and all I can 
do at present is to discuss critically several explanations which might be 
offered regarding its nature. 
(1) The absence of any structure or stages of reproduction in this body, 
as well as its great polymorphism, render very doubtful the supposition that 
it represents an unknown parasite of ciliates. 
(2) It might be supposed that it is derived from the macronucleus of the 
ciliate by longitudinal division. The occurrence of a double macronucleus is 
already known in ciliates of the family Anoplophryinae. It was first described 
by Schneider (1892) in Hoplitophryd sp., an intestinal parasite of a fresh-water 
Oligochaete, among several specimens of which he found 3 or 4 individuals 
with two macronuclei. These abnormal ciliates showed an ordinary multiple 
or catenular process of segmentation during which both macronuclei under¬ 
went a similar division. 
Double macronuclei were also observed by Leger and Duboscq (1904, 
p. 343) in Anoplophryd bmsili, an intestinal parasite which they discovered in 
Audouinid tentdculdtd Mont. As to the origin of the two parallel macronuclei, 
they do not agree with Schneider (1892), who supposed them to arise from an 
abnormal conjugation: they explain them, on the other hand, as a result of 
an ordinary longitudinal fission of a single macronucleus. 
But even if we admit the occurrence of longitudinal cleavage of the macro¬ 
nucleus in Anoplophryinae, this process will not explain the origin of the 
supplementary chromatic body in M. novd, for the following reasons: (d) the 
form and structure of the chromatic body differ very much from those of the 
macronucleus, (b) there is no continuity between these two structures, and 
(c) the chromatic body never undergoes segmentation when the macronucleus 
divides. 
(3) The chromatic body does not originate from the micronucleus, as in 
almost all specimens of Mdupdselld which contained it, the micronucleus 
was normally developed. 
(4) Its oiigin cannot be interpreted as a result of abnormal conjugation, 
as this process of reproduction has not yet been observed in Anoplophryid 
parasites of earth-worms. 
(o) It could be suggested also that this body is related to the so-called 
spicule, an endoplasmic rigid body which normally exists in other Anoplo¬ 
phryinae parasitic in earth-worms, namely Mesnilelld secdns Stein, M. clavata 
Leidy, M. spiculdtd Warpachowsky and M. fdstigdta Mobius. Unfortunately 
