1913] Kofoid-Sweztj: Trichomitvs terniiticlis 29 



that locomotion by Trichomitus in the midst of the seething mass of 

 parasites in the digestive tract of Termopsis, involves not a little 

 expenditure of energy. It is also conceivable that the conditions of 

 life therein are subject to marked variations incident not only to the 

 food and feeding of the host but also to the varying constituents of 

 the enormous mass of parasitic associates and their changing meta- 

 bolism due to phases of their reproductive activity. Biochemical 

 changes of no small import are consequently a feature of this crea- 

 ture's environment. That some of these are peculiarly fatal to 

 Trichomitus is evident from the unusual numbers of moribund or 

 cytolized individuals, each represented by a more or less decadent 

 nucleus and its attached neuromotor apparatus, which may be found 

 in most smear preparations. 



Considerable changes in extent and volume of this structure are 

 apparent upon an inspection of our figures, and even more so in our 

 preparations. These are indicative of changes resulting from meta- 

 bolism, or miiltiple fission, or both. In addition to the storage or 

 reservoir function it is apparent that the parabasal in Trichomifus 

 serves also as a somewhat rigid organ of attachment for the undulat- 

 ing membrane. 



The other organs of the neuromotor system, the paradesmose and 

 its rhizoplasts will be discussed in connection with mitosis. The 

 paradesmose is a more or less temporary organ in most triehomonads, 

 but in Trichomitus the organism appears to pass a much greater part 

 of its existence in what is comparable to the prophase stage of tricho- 

 monad mitosis, so that the paradesmose is actually present, suspended 

 bj' rhizoplasts from the blepharoplasts (fig. A, 5), and the whole neuro- 

 motor system is in some phase of duplication in many of the individuals 

 which we have seen. The stage with a single centroblepharoplast and 

 rhizoplast (fig. A. 1, 2, 6) is relatively much less common in this 

 species than in other triehomonads. This prolongation of the pro- 

 phase is the first step towards diplozoic organization such as we find 

 realized in Giardia, where nuclear division is added to that of the 

 duplication of the neuromotor system with the resulting formation 

 of a coordinating system for multicellular organization. 



Nucleus 



The nucleus (fig. A, n.) is a symmetrical ellipsoidal structure, 

 or even ovoidal or pyriform, with the wider end posterior (fig. B, 1). 

 The longer axis is two to three times the shorter one in length. It 



