Published online by Cambridge University Press: 06 April 2009
The development of T. lewisi in the blood of the rat is accompanied by a division of the nucleus which is more like an amitosis than a mitosis.
The division of the blepharoplast, always preceded by the division of a karyosome-like granule, might be called a promitosis (sensu: Nägler, 1909).
It is not proved that autogamy or parthenogenesis takes place in rats' blood or in cultures. The evidence brought forward by Prowazek and by Moore, Breinl and Hindle proves only the existence of chromidia; neither are Schilling's recent proofs suggestive.
Under abnormal conditions hypertrophy takes place affecting the nucleus and the blepharoplast, with subsequent formation of chromidia and final fragmentation. Similar stages found in the rat-louse have been described as sexual cells.
Considering these results in connection with previous observations of Strickland and myself, we may conclude that as yet nothing whatever indicates the occurrence of any sexual process in the life-cycle of T. levrisi, both in the vertebrate and invertebrate hosts.