INTRODUCTION. 13 
formed. The chromatin constituents of the nucleus first show a 
coarser arrangement, which is followed by the ''spindle stage," 
exhibiting an equatorial plate with achromatic fibres converging 
at the poles. In BadJiamia, Physarimi, Craterium, Didymium, 
Stemonitis, Lamproderma, and Comatricha the plasma at this 
period bi-eaks up into lobed masses containing six to ten nuclei ; 
the equatorial plate of each nuclear spindle now divides horizontally, 
and as the two halves draw apart the lobed masses of plasma 
undergo a further division, until the time when the daughter- 
nuclei have widely separated. Though still connected by achro- 
matic fibres, each pair is enclosed in a portion of plasma of the 
capacity of two spores; these portions become constricted into 
the ultimate spores, each containing a single nucleus : in a short 
time the spore wall is acquired, and the active stage of the 
organism comes to a close. In the genera just mentioned, spore- 
formation occurs in warm weather about twenty hours after 
the sporangia have taken 
form. In Trichia the in- 
terval is much longer, ex- 
tending from two to four 
days according to the tem- 
perature. In this genus and 
also in Ai'cyria, Lycogala, 
and Reticularia Lycoperdon, 
the spore-plasm is not seen 
to separate in lobed masses 
at the time when the 
nuclear spindle is formed, 
but the karyokinetic pro- 
cess is completed and the 
daughter - nuclei are de- 
finitely parted from one ^}°'^ * stained preparation of a young spor- 
„ .1 f P , angium, showing the Plasmodium separated into 
anoiner Oerore tlie plasma masses of two spores' capacity round the nuclei 
breaks up and encloses each ""ji^n'rd mo tiS'^^ karyokm^is. 
nucleus in a young spore.* 
The sporophores of Geratiomyxa are columnar, or confluent and 
interlacing. In their early stage the protoplasmic matter spreads 
throughout the superficial part of the columns, and also in 
numerous veins traversing the watery gelatinous interior sub- 
stance. These veins are ultimately withdrawn to the outer layer, 
which divides into polyhedral portions of equal size, giving an 
areolated structure to the even periphery ; each portion contains 
a single nucleus 2-5 in diameter. The whole sporophore is 
invested by a thm hyaline layer. The material of tliis investing 
layer and the interior gelatinous substance take a bright red 
colour m preparations stained in picrocarmine, which contrasts 
with the yellow tint of the protoplasmic matter. The contents of 
the o^n5iT« 'Y'''''''' Observed by taking slainiiigs, at short intcryals, of 
WhPr H-i " .si.orangia which have risen togotiier at one time ; 
further details are given m Linn. Soc. Journ., vol. xxix., p. 629 
Fig. 8.— Cojiatbicha obtusata Preuss. 
