Annals of the Transvaal Museum. 
243 
A reference to the plate will help to explain the whole life-cycle of 
Theileria parva , and the more important forms of the parasite as seen in 
the microscope are shown. 
With the bite of an infected tick, small uninuclear forms arrive in the 
blood circulation of cattle, and undergo further development in the organs, 
more especially in the lymphatic and haemo-lymphatic glands, in the bone 
marrow, and in the spleen (figure 1). These small parasites represent the 
sporozites or, according to Hartman’s nomenclature, the agametes of the 
first or metagame tic generation. They are only found after the ticks 
have moulted, that is, at the time when the tick is ready to seek a new 
host. I have not yet been able to trace these forms in cattle, and I have 
not found them in clean ticks (not infected), control ticks, or in ticks which 
have become purified by biting. 
If we carry out a systematic puncture of the glands and an occasional 
puncture of the spleen, commencing on the first day of the disease — that 
is to say from the day on which the tick attaches itself — we are able to 
trace the further development of the parasite. The superficial cervical 
and precrural glands are the most convenient for puncturing purposes. 
The first forms of the parasites are occasionally found on the twelfth or 
thirteenth days, but it is difficult to state the exact date, as the incubation 
time varies in the different experiments. These parasites reach the size 
of about 0 ’ 8 to 1 micron, and at first are found free. During the following 
days they are seen intracellularly, i.e. in the large lymphocytes, and very 
rarely in other leucocytes. They grow in size rapidly within the next 
few days (figures 2, 7 a, and lb). These agametes increase in size, and 
after multiplication of the nuclei grow into agamonts which finally split 
up into as many segments as there are nuclei. On an average the agamont 
measures about 10-12 microns, rarely 12-15 microns. 
Naturally the larger ones contain the greater number of nuclei. In 
the intracellular forms a considerable number of segments, agametes of 
the second generation, are frequently found, caused by double infection. 
As a result of this parasitism, the lymphocyte is destroyed and accordingly 
it is not surprising to meet irregularly formed agametes if the infected 
lymphocyte dies off before the agamont has divided into its daughter 
forms. 
Division of the nuclei takes place by amitosis ; in exceptional cases 
we meet indications of primitive mitosis in moist fixed smears or sections. 
The number of nuclei increases very considerably by successive fission 
processes, and may amount to more than forty or fifty. The form of 
the nuclei and their structure is characteristic for the process of agamogony. 
The nuclei do not possess an envelope, they have an irregular rugged form 
and no compact structure. During life they do not appear very retractile, 
they do not show much affinity for the various stains. When stained 
with haemotoxylin or giemsa, fixed and treated by the moist method, 
the stain easily escapes from the nuclei. The development of the agametes 
from the youngest to the full-grown agamonts (figure 2 a and b, figure 6a 
and b) and to succeeding schizogony into agametes (merosoites) can repeat 
itself. 
