MICROSCOPIC ORGANISMS IN INTESTINAL CANAL. 271 
sequent development of the spores. ‘The assumption of activity 
is retarded, but a certain number of the spores survive and sub- 
sequently give vent to Amcebe. Prolonged boiling, however, 
is certainly fatal to them. They are capable of surviving a 
twenty-four hours’ immersion in Liquor Iodi, remaining seemingly 
unaltered, and becoming active on the substitution of the reagent 
by a nutritive fluid. They can also survive immersion for several 
hours in 1 per cent. solutions of rectified spirit and of the phar- 
maceutical acetic acid. Mineral acids, even in very small pro- 
portions, appear to be fatal to them, and hydrochloric acid also 
immediately reduces any which are spherical to the biconcave 
form. ‘The capacity for resisting various external influences is 
also regulated in some degree by the condition of the body. It 
is only the condensed biconcave spores which are capable of any 
decided resistance, those which are in the dilated spherical con- 
dition being much more susceptible to detriment. 
Prolonged desiccation appears to influence the rate at which 
" activity is developed, but certainly is not fatal. A careful series 
of experiments on this point showed that whilst Amcbule 
began to emerge from ‘perfectly fresh spores within periods 
ranging from fifteen to twenty-five minutes, a gradual retarda- 
tion of the process corresponding with different periods of desic- 
cation manifested itself, so that, after a period of eighty-two 
days, emergence did not occur until within between five to 
twenty hours’ exposure to favorable conditions. 
When sporangia are introduced into preparations of fresh- 
boiled cow dung they rapidly disappear, and the cultivation 
within twenty-four hours, in favorable cases, shows an abundant 
new crop of sporangia. This process may be repeated again and 
again indefinitely so long as a fresh medium is supplied for each 
experiment ; for, as in the case of the natural development, the 
soil appears to be exhausted in the process of producing a single 
crop. Asa rule, in these cultivations we do not find a zoo- 
sporic stage represented, the spores at once giving origin to 
ameeboid bodies, which, after having increased in size, become 
associated to form new sporangia. ‘I'he crops of ‘sporangia thus 
produced are, as a rule, peculiarly abundant and well developed 
as compared with natural ones, due, no doubt, to the compara- 
tive freedom which the organisms here enjoy from a struggle for 
existence. In some cases, however, in these artificial cultures 
we find a failure of development or a failure of sporangial forma- 
tion, the surface becoming covered with a bloom of encysted 
Ameebee. 
Both in natural and artificial cultivations there is a distinct 
tendency to periodicity in reference to sporangial formation. In 
the notes regarding one case which were previously given, it is 
