38 Some Aspects of the Algce. 
the processes of development and escape of zoospores and gametes. 
The zoospores produced by an algal cell are regarded as being 
modelled from the middle region of the layer of protoplasm 
surrounding the central vacuole, each round a definitively formed 
nucleus. In this way the hyaloplasm of vacuole wall and ectoplasm 
come to be left over, together often with a certain quantity of inter¬ 
stitial protoplasm. Ectoplasm and vacuole wall are not regarded 
by the author as having an autonomous existence as special organs 
of the cell. 
In his general remarks on the developmental processes of 
the female gametes, Professor Oltmanns concludes that none of 
the processes of maturation, not even the striking phenomena 
exhibited in the Fucaceae,canbe directly compared with the formation 
of polar bodies by the animal egg, since polar body formation is so 
constant that it must presumably have a universal significance, 
while the phenomenon of “cast-out” nuclei in Fucaceas is entirely 
dependent on the number of mature eggs to be formed in the 
oogonium. Professor Oltmanns compares this last phenomenon 
rather with the production of nutritive or follicle cells from the 
sister cells of eggs in Daphnidae and Insects. He does not, as we 
understand him, deny that in all such instances (including polar 
body formation) the cells which do not become eggs are to be 
regarded as reduced members of a brood of gametes—as Hartog 
long ago pointed out—of which the functional egg alone becomes 
mature and developes at the expense of its sisters, but he thinks 
that polar body formation is a specialised case of this, connected 
with the reduction division, and only to be indirectly compared with 
the phenomena found among the algae. The somewhat mysterious 
behaviour of the nuclei discovered by Klebahn in certain Diatoms 
our author considers as the remnant of an ancestral formation of 
a brood of gametes such as Karsten finds in Corethrou, while the 
two nuclei in each of the two embryos formed from the zygotes of 
Cosinarium and Closterium are similarly supposed to be reminiscent 
of ancestors, which, like the Mesotaeniaceae, normally produced four 
embryos from the zygote. Professor Oltmanns’conclusions appear 
to take us as far as we can safely travel in the light of the facts at 
present known. Whether any or all of the nuclear phenomena in 
question can also be related to the process of chromosome reduction, 
which must take place at one stage or other of the life cycle in all 
sexual forms, the future alone can show. 
There is a good general account of the conditions under which 
