108 Recent Literature. [ZOE 
ization. The opening pages review Guignard’s discovery of the 
‘* attraction spheres’’ and ‘‘centrosomes,’’ structures long known 
in animal cells, but not hitherto certainly demonstrated in those 
of plants. These Strasburger regards as essential constituents 
of the cell, and therefore assumes that they must take part in 
fertilization, which can no longer be regarded as consisting in 
the union of the sexual nuclei alone. 
Before passing to the consideration of the zoospores the author 
describes for the first time the occurrence of the attraction spheres 
in an alga—Sphacelaria scoparia—in which he found these easily 
demonstrable, and concludes as they have been found in so many 
widely diverse forms, that they are probably always present when 
there is a separation of the protoplasm into cytoplasm and nucleus. 
For the protoplasm radiating from the centrosomes, and that 
composing the spindle-fibres and connecting threads of the kary- 
okinetic figures, he proposes the name ‘‘kinoplasm,’’ and sup- 
poses it to play an important part in nuclear division. 
The development of the zoospores was carefully studied in a 
number of algze belonging to different groups. ‘The most impor- 
tant conclusions reached were that the transparent end of the 
zoospore is composed of kinoplasm that gives rise to the cilia 
which are formed as outgrowths from it. The envelope in which 
the zoospores are often contained when first ejected from the 
mother-cell, is the outer protoplasmic layer (Hautschicht) of the 
mother-cell, and not part of the cell-wall as hitherto supposed. 
Comparing the development of the non-sexual zoospores with 
that of the gametes or sexual ones, and also of the spermato- 
zoids of higher cryptogams, he points out clearly the common 
nature of all these forms. In Chara fragilis, according to his 
account, the forward, cilia*bearing coils of the spermatozoid, orig- 
nate as a cytoplasmic appendage of the nucleus, and the hinder 
coil is also of cytoplasmic origin, and corresponds to the hinder 
granular part of azoospore. Only the middle coil is composed of 
nuclear substance, instead of the whole body of the spermatozoid 
as has been supposed. The forward coil gives rise to the cilia in 
the same way as the clear forward end of a zoospore does, and 
like that he considers this to be composed of kinoplasm. In 
mosses and ferns, only the small forward coils of the spermato- 
