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dry air to the water in which the animals are living, succeeded 
best. In this way he kept specimens twelve hours. The 
stages observed are—Ist. Noctiluca-like bodies, but without 
mouth or lash, and having a doubly spherical or so-called 
biscuit form, each partial sphere havinga granular protoplasmic 
mass with fine branching rays, the two masses being connected 
more or less. 2nd. The protoplasm collects so as to form a 
disc on one pole of the irregular double spheroid, which 
gradually becomes spherical, exhibiting three or four depres- 
sions at one pole. 3rd. The protoplasmic disc sends out 
stumpy processes which project from the surface of the 
spheroid and exhibit peculiar wriggling movements. 4th. 
The mass commences to divide into smaller pieces, the vesicle 
being now quite spherical. The commencement of this division 
was not directly observed, but later stages, in which clumps 
of protoplasmic matter were seen arranged at first in groups 
of eight; these, then, were followed carefully through their 
division into groups of sixteen irregular, oblong particles. 
These products of division appear like denser, sharply-defined 
masses or nuclei, lying in a less dense surrounding granular 
plasma. oth. The next stage was one of the first and most 
commonly observed, in which the protoplasmic disc, formed 
as above described, has become entirely split up into small 
oval bodies, each -016 milliméter long. The aggregated 
mass of these oval spores sometimes appears as a disc at one 
pole of a Noctiluca-like vesicle, or as a girdle passing round 
it. 6th. By high powers each oval particle is seen to have 
a terminal cilium, and whilst under observation many were 
seen to separate from the disc and swim about as free swarm- 
spores: such as that drawn in woodcut fig. la; fig. 10, and 
c, are later stages of the free development of the swarm- 
spores. ‘The large development of the process ¢ is very 
interesting. Professor Cienkowski thinks it not improbable 
that this becomes the ‘ tooth” of the adult Noctiluca. The 
further development of these spores was unfortunately not 
- traceable, and there are some difficulties in attempting to 
harmonise their appearance with young Noctiluce, as described 
by previous authors. 
A further point, however, of much importance, is established 
by Cienkowski. He has succeeded in observing, step for 
step on the stage of the microscope, the copulation of the two 
Noctilucee. The two animals place themselves with the two 
so-called “ oral apertures” close to one another, and through 
these a protoplasmic bridge is formed, which unites the 
nuclei of the two individuals. Later, at the points of contact, 
