12 THE GEELONG NATURALIST. 
mass of spirogyra in the pond, two filaments lie side by side, the 
first thing that happens is that two parts of the cell walls on the 
opposite filaments protrude toward each other, this growth continues 
until the parts meet, and nothing separates the two cells save the 
partition wall formed by the ends of the outgrowths. Inthe mean- 
time a great change may be observed in one of the cells. The whole: 
of the contents become disorganized and the particles after a great 
deal of movement coalesce unto a heterogenous mass known as a 
motile gamete. More changes occur, the partition wall is absorbed, 
thus leaving a free passage between the cells, and the contents of 
the other cell behave in the same manner and form a resting gamete. 
The motile gamete (as its name implies) has the power of movement, | 
and begins to pass slowly from its own cell through the passage: 
into the opposite cell, here it unites with the resting gamete, and 
the two protoplasmic masses thus united form a dense rounded mass 
which covers itself with three coats, the middle one being very thick 
and so formed as to resist the effects of the most intense heat. 
This body is known as a zygaspore and contains the vital principal 
under the most trying conditions, the pool may dry up, the parent 
plant may wither and die, but the zygaspore safely covered will 
sink into the mud, and if the mud be changed into dust and a. 
quantity be blown away some of these zygaspores are sure to remain 
until there is more rain. When the rain does come and the hollow 
is refilled with water, the spore gradually softens and swells, and 
after a longer or shorter time the swelling increases to such an ex~ 
tent that one end of the spore bursts, and a new plant begins to 
sprout. It continues to grow until a full sized filament is formed, 
with the cells and contents exactly the same as those described at 
the commencement of this lecture. In conclusion, I may remark 
that Spirogyra is only a single genus amongst hundreds of different 
water plants that are preserved in a somewhat similar manner. 
ese 
THE EOCENE DEPOSITS OF CORIO BAY. 
By J. F. MULDER. 
TTE north western shores of Corio Bay are bounded by cliffs of considerable: 
height. On the top of the cliffs isa layer of ironstone nodules, beneath 
which lie deposits of drift sand and gravel, also stained with iron oxide. 
Under these drifts the Eocene sands commence, in which Pecten Yahlensis,. 
Spondylus pseudoradula, Waldheimia Corioensis, and Balanophyllia 
armata are the most conspicuous fossils. The sands continue down to high 
water mark, when the material becomes moreargillaceous, and thefossils found 
shew considerable resemblance to those o£ Fyan's Ford, on the Moorabool 
River. Mixed with them are some restricted species, and others similar to 
those at Curlewis; in fact, this and the adjoining bed on the Eastern beach.. 
