Zoology. 255 
(generic and specific) of all the ferns of the world. It is not to 
include descriptions, but references are to be given in every instance 
to descriptions. Synonyms will be given, and the distribution of 
every species will be indicated. It promises to be a very useful 
book. Miss Jane H. Newell, of Cambridge, Mass., has begun 
the publication, in parts, of a little work to be called “Outlines of 
ns in Botany,” designed to be of use to teachers who wish to 
do more than follow the old methods of botanical teaching. The 
lessons outlined “are suitable for children of twelve years of age 
and upwards.” Directions are given for raising seedlings, and for 
making observations upon them in their growth. ‘The parts before 
us are privately printed, in order to have them. tested by other 
teachers before publication. They may be obtained by any teacher 
who will use them experimentally, by addressing the author at 175 
Brattle street, Cambridge. DeBary’s Lectures upon Bacteria, 
English translation, has been received from Macmillan & Co. It 
is a small work, of a sufficiently popular style to enable any well- 
educated man to get a good idea of the subject. A fuller notice 
will appear later. Detmer’s Pflanzenphysiologische Praktikum,, 
from Gustav Fischer, of Jena, promises to be a most valuable book 
in the botanical laboratory. It is an octavo of 352 pages, and is 
illustrated with 131 wood-cuts. Dawson’s “ Geological History 
of Plants” is an interesting volume of the International Scientific 
Series, which has just appeared. The style is popular, but the 
treatment is thoroughly scientific. 
ZOOLOGY. 
: again 
J differentiating a male and female pronucleus. In the next 
ge (E) the male elements of the two conjugating Protozoa are 
exchanged, and the new male nucleus fuses with the original female . 
1) the ex-conjugates reassume their original organization 
before dividing for the first time. : 
What is the meaning of all this? There is no special sexual 
tion or generation. There is no acceleration of division 
er conjugation. It is a period of risk, especially during the 
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