289 
impossible to attempt a far-reaching study of the parasite. Never¬ 
theless, a fairly complete description is given of some forms constantly 
observed. This is done with the purpose of insisting on what an 
excellent object for study this type of parasite is ; especially since 
some of the forms seen seem in some measure to harmonise with 
Schaudinn’s description 4 of the development of Spirochceta ziemanni 
in the blood stream. 
Schaudinn gives no particulars but simply states that the development of 
Spirochala ziemanni differs in no important point from that of Hamoproteus noctuee. 
In our specimens the forms already frequently descnbed as 
makrogametocytes (figs. 66, 67, 69, 72, 73 ). and mikrogametocytes 
(figs. 48, 49) are easily recognisable, and in the main their 
appearance is in accord with previous descriptions. It is noticeable 
that in all forms of the parasite the nucleus of the host-cell is but 
little flattened, and practically never takes the dumb-bell-like shape 
described by former observers in similar parasites. The position of 
the host nucleus in the adult parasite varies according to the position 
in which the parasite dries on the slide. Although it is usually- 
placed laterally at a point about midway between the two extremities 
of the parasite (fig. 49), it may occur in any position. It has frequently 
been extruded (fig. 65), and gametocytes without any included host¬ 
cell nucleus are not uncommon (fig. 66). 
The general structure of the parasites of each sex at all stages of 
development is the same. Each parasite has periplast, ectoplasm, 
endoplasm and nuclear bodies. The “ periplast ” consists of a non- 
granular, pink-staining (always ?) sheath which invests the whole of 
the parasite. In it run fairly numerous faint, non-staining, longitudina , 
or, if the parasite is twisted, apparently diagonal striations (these can 
be seen by careful examination in even the youngest parasites). I he 
periplast with its striations is, as a rule, best seen in the more 
lightly staining mikrogametocytes (fig. 5 °)- tlie aclu ^ ^ or ” ls 
the periplast is prolonged at either extremity into long slen 
processes. When the matured parasite becomes rounded, preparatory 
to conjugation, the periplastic sheath (fig. 7/) 4S thrown off toget er 
with the effete host-cell nucleus 1 (fig. 3 1 )- 
A similar process probably occurs in the change from the testing 
to the motile stages (Schaudinn) 4 . 
Appearances in young parasites (Plate XX), as well as in t e 
