i8o Wager.— -The Life-history and 
a spiny wall. Both may be found in the same culture, but the spiny form 
seems to be the normal one, and is produced under the more favourable 
conditions of food supply in the early stages of a culture, the smooth form 
being produced, sometimes in great abundance, during the later, less favour- 
able conditions. In both cases the gametes are placed in contact with one 
another by a delicate pseudopodium-like process, which is put out from the 
male gamete. These copulating pseudopodia are of varying length, some- 
times very short (Fig. 4), at other times extending to a considerable distance 
before they can reach the female gamete (Fig. 1). Whether there is any 
definite attraction between the two gametes, or whether it is merely a chance 
encounter, I have not been able to determine. The copulating pseudopodia 
do not differ in any respect, except possibly that of extreme length in some 
cases and absence of branching, from the ordinary haustoria which penetrate 
the Euglenae. 
In the case of the spiny form the zygote is produced by the swelling 
of the apex of the pseudopodium near its point of contact with the female 
cell (Figs. 1-5). The smooth-walled zygote is formed, on the other hand, 
according to Nowakowski (’ 76 ), as a globular outgrowth from the female cell 
just where it comes into contact with the male pseudopodium. I have not 
been able to observe this second method of zygote formation, although 
I have seen the production of both spiny and smooth- walled zygotes. So 
far as my observations go, the zygotes are formed in both cases by a swelling 
of the apical portion of the male pseudopodium in contact with the female 
cell. Dangeard also (’00), who has made observations on the formation of 
the smooth-walled zygotes, describes them as swellings on the pseudopodium 
of the male cell, and he further remarks: ‘We have seen nothing which 
allows us to postulate with Nowakowski a different manner of formation 
for these two kinds of zygotes.’ 
The following observations on the formation and maturation of the 
zygote refer to the spiny form. Immediately following the appearance of 
the zygote, the protoplasmic contents of the male cell pass through the 
delicate pseudopodium into the zygote (Fig. 5). A perforation appears in 
the wall between the young zygote and the female cell (Figs. 3, 5), and the 
contents of the latter pass through it into the zygote (Figs. 59, 60). 1 
The zygote is then cut off by partition walls from the remains of the 
two original gametes. The whole process, from the time of the first appear- 
ance of the swelling on the pseudopodium to the complete separation of the 
zygote, takes about twelve hours or less. The contents of both gametes 
include a large number of oil-drops, and in some cases the nuclei of the 
living cells can be clearly made out. 
1 In all the cases which I have observed, the male nucleus first of all passes into the zygote, then 
the female nucleus, but Dangeard (’00), in describing the formation of the smooth-walled zygotes, 
states that the female nucleus ordinarily passes in first, then the male. 
