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THE AMERICAN NATURALIST [Vol. XL VI 



dents who have expended considerable time and "gray matter" 

 on the problem of the forerunner of the vertebrate notochord 

 the reviewer would heartily welcome a demonstration that the 

 organ "may be recognized in practically all segmented inverte- 

 brates"; but until a clearer, more convincing description is fur- 

 nished us of some structure in "practically all segmented inver- 

 tebrates" with which the vertebrate notochord is to be com- 

 pared, the question of homology in the strict sense would not 

 even be raised were the best interests of comparative anatomy 

 duly considered. 



The other defect in the presentation of matters-of-fact which 

 a well -wisher for the book may justly fear will tend to prevent 

 as wide use of it as it deserves, is the circumstance that several 

 modes of statement occurring over and over again are bound to 

 give even the fairest-minded reader the impression that many 

 of the facts were prejudged ; that is, were collected and recorded 

 not primarily on their merits, but in behalf of a theory. The 

 nomenclature employed in several important connections is 

 likely to have this effect. The use of the substantive cephalon 

 with various prefixes in purely descriptive matter dealing with 

 the thoracic region of arthropods is an example. 



In the chapter "Minute Structure of the Brain and Cord of 

 Arachnids" we read (p. 80) : 



The more posterior thoracic commissures, and those in the hindbrain, 

 are shorter, and the neural and haemal fascicles are widely separated, 

 leaving a space between them, which represents the beginning of the 

 fourth ventricle (italics by the reviewer). 



Such dogmatic and uncalled-for statements inserted into 

 purely descriptive matter are very unfortunate, for they can but 

 militate against the factual value of the work in the mind of 

 every candid reader. The feeling of uneasiness engendered in 

 the reader by these gratuitous dogmatizings, as to the extent to 

 which facts dealt with have been unconsciously colored by 

 theory, is not allayed by the author's avowed attitude toward 

 the facts of organic structure. On page 469 we find this : 



Comparative morphology has no value except in so far as it points 

 out the historic sequence of organic forms and functions, and reveals to 

 us the trend of evolution and the causes that direct and control it. 



This statement I insist is not true. It may be partly true, but 

 in the unqualified form given it by the author is not only untrue, 

 but is provokingly and harmfully untrue. If for Dr. Patten 



