OCCURRENCE OF NUCLEAR DIMORPHISM IN HALTERIDIUM. 349 
—whatever it may be—in which the Halteridial parasite 
enters the blood from the Invertebrate host, in this case a 
Lynchia, passes first into one of these endothelial cells. In 
this position it grows and subsequently gives rise to a 
progeny of little individuals, which, when set free, penetrate 
the red corpuscles and become the well-known Halteridia. 
I have no doubt a similar process occurs in the case of the 
parasites of the chaffinch. Most unfortunately I omitted 
to make smears from the lungs. In a smear from the bone- 
marrow, however, I have come across two instances of a phase 
which, | believe, corresponds to the segmenting forms 
described by Aragao. One of these parasites is drawn in text- 
fig. 14. Itis free, having evidently broken loose from the cell, 
perhaps a leucocyte, in which it was parasitic. It is in pro- 
cess of multiple division, possessing several nuclei. The 
most interesting point to notice is that some of these 
nuclei show nuclear dimorphism. Associated with the larger, 
more obvious nucleus is a small, deeply-staining grain, which 
probably represents the kinetonuclear element. ‘Two or three 
of these “double” nuclei closely resemble the double nuclei 
of the minute Halteridia in the red blood-corpuscles (cf. 
text-figs. 12 and 14). Unfortunately, the specimen is rather 
darkly stained, and I cannot be sure of this feature in all the 
daughter-nuclei. 
The connection of Halteridium with a parasite of cells 
other than red corpuscles (endothelial cells, leucocytes, etc.), 
made known by Aragao, furnishes another link in the com- 
plicated chain of events, which, according to all indications, 
make up the complete life-cycle of this form. Itis instructive 
to note that Leishmania donovani, which is now admitted 
by everyone to be the intra-cellular phase of a Flagellate, is a 
parasite of such cells; and it is not yet certain whether it 
invades the red corpuscles. Halteridium is probably a 
stage in the life-history of a 'Trypanosome, which has advanced 
a step further and become adapted also to the red corpuscles. 
THe Lister Insriruve, 
December 10th, 1908. 
