12 
INTRODUCTION. 
In examining the rising sporangia of Physarum nutans in 
a moist chamber under the microscope, the projecting masses of 
Plasmodium are seen to pulsate, distending and shrinking as the 
rhythmic flow advances or retreats, but gradually gaining with the 
advancing movement. The basal part of each contracts and forms 
a stalk consisting of a tube of tougher hyaline substance through 
which the protoplasm continues to pass until the surrounding veins 
have emptied their contents into the spherical sporangium. The 
coarse refuse matter which has not been discharged along the track 
of the Plasmodium, where it often takes the form of a hypothallus 
connecting the sporangia, is deposited in the centre of the stalk. 
When the young sporangium has attained its full dimensions, 
the wall thickens, and a 
part of the lime granules 
which abounded in the 
Plasmodium is incorpo- 
rated in the wall-sub- 
stance ; the remaining 
part is collected into the 
lime - knots or vesicular 
swellings of the hyaline 
threads of the capilli- 
tium ; these threads 
branch and anastomose, 
forming a network which 
spreads through the 
spore - plasm from the 
base of the sporangium 
to its wall. The forma- 
tion of spores takes place 
after the capillitium has 
been developed in all 
,. . , , . . _ - . the ffenera which are 
kinesis ; the nuclear division has reached the "spindle , , • i ^ •, 
cases hut characterised by its pre 
Fig. 7. — Comatbicha obtusata Preuss. 
From a stained preparation of a young sporangium, 
showing the ijlasmodiura separated into rounded masses 
ahout gioups of nuclei, which are dividing by karyo- 
the spindles are seen in profile in all 
one'in which the equatorial plate is seen from one of gencC. In Diclvmium 
the poles of the spindle. ^ , . i i i 
Magnified 1200 times. the lime-granules which 
can be seen in the 
Plasmodium are dissolved in the sporangium, and the salt in 
solution passes through the soft sporangium -wall and forms 
into crystals on the outer surface. The various kinds of 
capillitium represented in the different genera and species are 
described in the text. The formation of spores in the Endo- 
sporece is preceded by the division of the nuclei in the spore- 
plasm by karyokinesis. The processr was first recorded by 
Strasburger as occurring in Trichia fallax.* Recent observa- 
tions show that this mode of nuclear division takes place in the 
sporangium only once, and occurs almost simultaneously in all 
the nuclei rather more than an hour before the spores begin to be 
* Botanisclw Zeitung, May 1884. 
