1899] FLORE AT WOOD'S HOLL 385 



portant part in developmental processes. In the fifth lecture Mr. A. L. 

 Treadwell discusses equal and unequal cleavage in Annelids, in regard 

 to which he seeks to show that equality of cleavage is not an indica- 

 tion of lack of differentiation in the ovum, for definite cells appear at 

 definite places and at definite times, just as accurately as in unequal 

 cleavage. The sixth lecture, by A. D. Mead, is more technical, dealing 

 with the debatable question of the origin and homology of the proto- 

 troch. In the seventh lecture Miss Cornelia M. Clapp discusses the 

 relation of the axis of the embryo to the first cleavage plane, and 

 reaches " the only reasonable conclusion " that while the first cleavage 

 plane may coincide with the median axis of the embryo, as Eoux and 

 others have shown, it is not a constant rule in any siugle case, much 

 less a universal law. Dr. Thomas H. Montgomery, jun., recounts his 

 observations on various nucleolar structures of the cell, and shows at 

 least that both false and true nucleoli are structures of manifold com- 

 plexity, in regard to which our knowledge is very vague. Dr. Watase 

 follows with a lecture on protoplasmic contractility and phosphor- 

 escence, in which he gently leads up to the conclusion that the true 

 physical basis of phosphorescence finds its closest analogue in the 

 common phenomena of heat -production, and is as extensive as life 

 itself. Professor T. H. Morgan discusses in the tenth lecture some 

 problems of regeneration, showing that it is not easy to solve them all 

 by quoting Lessona's law, or repeating the words " natural selection." 

 In the eleventh lecture Professor Bumpus, who has previously made 

 good use of sparrows, shows that they are subject to discriminate elimina- 

 tion. The twelfth lecture by Professor Jacques Loeb, on " The Here- 

 dity of the Marking in Fish Embryos," has been noticed separately. 



The late Mr. W. W. Norman, whose loss to science is deplored, 

 was the author of the thirteenth lecture, which shows that reactions of 

 lower animals upon injury furnish no safe evidence of pain-sensations. 

 Professor W. B. Scott discusses North American ruminant-like mammals 

 in his accustomed style, and then follows a fine essay by Professor 

 W. M. Wheeler on Wolff and the Theoria Generationis. But, in some 

 ways, the most impressive lecture is the last, in which Professor Whit- 

 man discusses animal behaviour, and furnishes a notable contribution 

 to comparative psychology. 



The charm of these lectures may be partly due to the circumstances 

 of their delivery, but it is doubtless mainly due to the fact that each 

 is an expression of personal work and personal interest. One cannot 

 but be grateful to the Laboratory at Wood's Holl, which has been the 

 stimulus of the fine series to which this volume is added. — Ploreat 

 Wood's Holl. 



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