F
 

^828
 

■»H-1IUU.|UI„J_,
 

bility which Mc
' that the visible i
and behavior of
or incidents of p
the real determi
and consistently"
opposed to a mo:
are, it would see
In conclusion, -
ieal  conceptions
author favoring

The average eqi-
dicates, I think, 1
regulate the resulf"
ological mechanisn
This physiological
separation of mal
,in the egg and sp
-duction of those co ■
tone or the other s
I the initiatory pro'
others in the sper
union of egg and !'

The final sectii-
?exual characters
jf the data on t
characters and 1.
discussion of th
secondary sexual

The book as a
book must be, a
luthor deserves t.
»gists for his at
cattered data ir
ixrjerimental zoo"
 

COLUMBIA  UNIVERSITY  LIBRARIES

This book is due on "the date indicated below, or at the
expiration of a definite period after the date of borrowing, as
provided by the library rules or by special arrangement with
the Librarian in charge.
 

DATE BORROWED
 

CJ:3 (449) M50
 

JL8_
 

-^
 

DATE BORROWED
 

T^oL. XXVI. No. ere

left to go over the
work out the re-
finding them pre-

_'ed to the various

ferences  to  these

_he text.   . The dis-

are obvious.     In

-igraphies   are  fai
 

ig of the figures
- cases.    Many ol

)arate figures: the
-.g. 1," "Fig, 2f-
_re also numbered,

I  cases  except ir

-lumbers  continur

In referring tc

is made in mosi
-. the single figure.

, 4, for example,
""'ig. 4 or the single
_)s.     The explana-

lis confusion less
-lerwise, but some

3ferable.

jsentation present
_  be  due  only tx3

letition is not in'-
~wo following sen-
_ges of each othei

le experiments of
 

jf material within the limits of a single vol¬
ume has necessarily resulted in a rather sum¬
mary treatment of various subjects and entire
omission of others. Moreover, since the au¬
thor has felt himself obliged to omit all con¬
sideration of experim.ental embryology, form-
regulation and anim_al behavior, his consider¬
ation of certain subjects is somewhat one¬
sided. Many of the facts in all these fields
have a most important bearing on the prob-

ems of heredity and evolution and one which

till awaits consideration.
The material which is presented is not al¬
ways fully digested.     Many of the chapters
lead like a part of some " Jahresbericht" and
 

ations and experi¬
ments show that external factors do not detf:. nine
the appearance of the sexual generation (p. 337).
Weismann carried out some experiments which
show, he thinks, that external conditions do not
regulate the alternation of generations   (p. 339),

And again in the account of the work of
Kellogg and Bell on sex determination in
silk-worms these two sentences are half a page
apart:

The chief interest of their work is their exam¬
ination of the possible effects of nourishment on
the second generation  (p, 377),

The possible influence of food in determinin
the sex of the egg (or sperm) was also examine
(p. 378).