668 MURIEL ROBERTSON. 
’. raiz in its external appearance and partly also in its 
movements in rather a remarkable manner, the most striking 
difference being in the situation of the trophonucleus which 
in I’. vittate lies much nearer to the kinetonucleus.! 
IJ. OBSERVATIONS UPON THE LIVE TRYPANOSOME. 
A great deal of time was spent in making observations upon 
the living object, as it is obvious that where possible it is by 
far the most satisfactory method. 
Trypanosoma vittatz in the live state is a pyriform 
organism with a well developed frilled membrane. ‘The frilled 
appearance is of course due to the membrane being longer 
from tip to tip at the free edge than at its origin from the 
protoplasmic body. ‘lhe trophonucleus can be clearly dis- 
tinguished as a circular body lying at no great distance in 
front of the kinetonucleus. It appears as a greyish sphere 
surrounded by a brighter halo: there is something very 
characteristic in the rather soft way in which the nuclear 
structures refract the hght, contrasting sharply with the very 
hard, bright appearance of the protoplasmic inclusions—this is 
alike true of 'l'rypanosomes and Hemogregarines. Striations 
' T have adopted the now very generally accepted terms of kineto- 
nucleus and trophonucleus for the small and large nuclear bodies 
respectively. These terms seem to me to express more adequately than 
any of those hitherto proposed the nature and function of these two 
structures. In this paper the expression 
equivalent to the flagellate end, ‘* posterior ” end as equivalent to non- 
flagellate end. The evidence in favour of this view being correct seems 
ee 
anterior’ end is used as 
quite convincing when one has regard to those Trypanosomes in which 
the Trypanosome phase is derived from a Crithidial or Herpetomonad 
form in the normal life cycle. The evidence for regarding the flagellate 
end as the anterior is not so clearly indicated in Trypanosomes which 
adopt the crithidial or herpetomonad condition by the mere alteration 
in shape of the body and the migration towards the flagellate end of the 
already existing flagellum. ‘This development, as is well known, is said 
to occur in the cultured forms of a very large number of different Try- 
panosomes, notably those of birds and mammals. 
