220 
Lambornella stegomyiae 
which are all known to be parasites of animals. Finally, however, by careful 
search under a high magnification, I have succeeded in demonstrating its 
presence. It appears as a small, lozenge-shaped, refractile spot (Fig. 2,1 and II, 
Cy.), interrupting the longitudinal striations of the body surface. It is ventral 
in position and forms a small groove, situated at a distance of 10/x from the 
anterior end of the body, and measuring 5 to 6/x in length and 2 to 3/x in 
width. The cytostome is most easily seen when viewed in profile. 
III. Reproduction. 
Reproduction of Lambornella stegomyiae takes place by simple, transverse 
fission. The micronucleus first divides mitotically, and when the two daughter 
micronuclei have appeared, the macronucleus undergoes an amitotic division, 
accompanied by a constriction of the body and fission of the protoplasm 
(Fig. 4, A and B). I have not seen any evidence of conjugation. 
Fig. 4. Lambornella stegomyiae. Two dividing specimens of the ciliate. 
IV. Encysted Stage. 
Among the hundreds of parasites seen within the bodies of the Stegomyia 
larvae, no cysts were present; all the ciliateswere in the active or trophic phase. 
One of the larvae only (see p. 218, No. 4) showed the cystic form of Lambornella. 
The external surface of the cuticle of this larva was studded with small, 
transparent, hemispherical vesicles, each of which enclosed a contracted mass 
of protoplasm (Fig. 5). These I first thought to be epizooic organisms such as 
are commonly found upon the bodies of fresh-water Arthropods. In stained 
preparations, however, the protoplasmic mass was seen to contain a nucleus 
so closely resembling in its structure that of Lambornella as described above, 
that no doubt remains in my mind: these vesicles are unquestionably the cysts 
of the ciliate. 
The cysts measure from 30/x to 40/x in diameter and 20/x in height (Fig. 6). 
The protoplasmic mass (22/x to 32/x in diameter) contains a contracted macro¬ 
nucleus (8/x to 10/x in diameter) with a peripheral depression in which the 
