130 MR. F. J. MEGGITT ON A 
Development. 
The development of the egg has not been fully worked out, but 
the results so far show a close similarity to those of van Beneden 
(2), who used Tenia serrata. 
Both fresh and stained material have been used; the results 
obtained by the use of the former give a connected series, but 
thers are gaps between the stages observed in stained material. 
Kraemer (10) appears to be the only investigator who has 
described the several stages in the development of the egg, but 
my own material does not agree at all with his description. 
The following results were obtained from fresh unstained 
material. 
When the eges pass into the uterus, they appear to consist of 
a transparent ‘colourless membrane, ‘021 mm. dia., containing a 
roughly spherical mass of uniform refractive grey yolk-granules ; 
this inner mass lies freely within the membrane, which only 
touches it at one or two points. Both the membrane and the 
inner mass increase ia size, but the former more rapidly than the 
latter, so that later on, the impression given is that of a grey 
ball, 025 mm. dia., within a large bubble ‘047 mm. dia, (Pl. I. 
fig. 15). From this point the membrane always preserves the 
same relative distance between it and the inner mass, and finally 
becomes the outer membrane of the onchosphere (m.). The yolk- 
follicles now begin to disappear, clustering together at one pole, 
the remainder of the inner mass being filled up by a fine grey 
granular substance, from which the agree ea hooks appear to 
originate. 
Meanwhile the inner mass has become aifercnttatd into a 
central mass, °023 mm. dia.—the future onehosphere—within an 
outer granular coat, *028 mm. dia. and ‘002 mm. thick (Pl. II. 
fig. 17), which at first touches it at every point, but later shrinks 
away to leave the onchosphere entirely free. By the time the 
yolk-follieles have disappeared the egg has become ready for 
discharging (Pl. II. fig. 19). It then consists of the oncho- 
sphere, ‘023 mm. dia., provided with six hooks, and closely sur- 
rounded by a delicate membrane. This is surrounded by the 
granular second membrane (m’.),°0385 mm. dia. and -002 mm. 
thick, the whole free within a transparent membrane (m.), 
°058 mm. dia. The hooks are :011 mm. long, ‘001 mm. at their 
broadest part, and the curved part is ‘(004 mm. long. Treatment 
with a solution of methyl green in | per cent. acetic acid shows 
that the second membrane has a circular poe: (0057 mm. dia., 
in it. 
Sections of the cestode killed with ete anle eels solution 
and stained with iron hematoxylin give the best detailed 
results. 
The ovarian eggs (Pl. alate fig. 24) are ‘017 mm. dia., very 
granular, and are surrounded by : a distinct membrane. A clear 
nucleus, ‘0092-0103 mm. dia., is present, containing a dark- 
