vol. XLI, NO. 485 



MAY, 1907 



THE 



AMERICAN 

 NATURALIST 



A MONTHLY JOURNAL 

 DEVOTED TO THE NATURAL SCIENCES 

 IN THEIR WIDEST SENSE 



CONTENTS 



I. Tli« Functions of the Spiracle of the Skate . . HEBBEST W. SAND 287 



II. A Critical and Statistical Study of the Determination of Sex, particularly in 



Human Offspring F. H. PIKE 303 



III. Chubs' Nests ALFRED W. G. WILSON 323 



17. Notes and Literature : General Biology; Mendelism— The problem of age, 



growth and death.— The hypothesis of mimicry. Zoology; Palms and 

 Soles. — Literature of Ichthyology. — Nettling hairs of the brown-tail 

 moth.— Divided eyes of insects.— Notes. Botany; Winter rest.— 



Notes 329 



V. Correspondence: The Flying Fish Problem 347 



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