N. H. SWBLLENaREBEL 
463 
change of structure is the production of a central clear space in the 
nucleus (fig. 3), the karyosome breaking up and forming a circle of 
chromatic granules round it. The granules may be equal or unequal 
(figs. 17—19). 
Prowazek (1905) has interpreted some of these stages (such as 
figs. 6—8, 10, 13—16, 18) as “autosynthesis” of the nucleus, by which 
the karyosome divides in four parts, two of them degenerating and two 
combining to form a new karyosome (cf. Prowazek’s figs. 5—8 with 
figs. 7, 14, 15, 18 of Diagram III). I think however that these forms 
selected by him out of a great variety of forms, have no more significance 
than any other of the nuclei of Diagram III so that I do not see that it 
is proved in the least that this autosynthesis really occurs. Minchin, 
who holds the same opinion, thinks that Prowazek’s views are based on 
an incorrect observation due to a defective technique, but I think his 
observations (not the interpretation) are quite right. 
Figs. 1 and 2. Flagellates of the chronic stage of infection with two nuclei, 
one of them pycnotic. 
Fig. 3. The same, but both nuclei pycnotic, one of them fragmented. 
The peripheral granules of nuclei such as are represented in 
Diagram III, figs. 1, 20, 21, are generally regarded as chromosomes and 
their number is said to be constant. This is not the case in the nuclei 
shown in Diagram IV. I do not think them to be real chromosomes, 
because they do not play any part in the nuclear division. 
Very large karyosomes nearly occupying the whole nucleus were 
never observed. I have already stated elsewhere the probability that 
they are due to shrinkage, the shrunken nucleus being taken for the 
karyosome (1910). 
