56 BIOLOGICAL SOCIETY OF WASHINGTON. 



especially commend the second of these articles as an alto 

 gether fresh presentation of the case, replete with facts from 

 the lowest forms of organized life. Many of these taken from 

 the vegetable kingdom come home to me with great force, and 

 it seems difficult to see how another interpretation can be put 

 upon them. 



Prof. Karl Semper published in 1881 as one of the Interna 

 tional Scientific series his Natural Conditions of Existence as 

 they effect Animal Life, in which he supports the same class 

 of views by many observations from his own profound studies. 

 Prof. Sidney H. Vines in his Lectures on the Physiology of 

 Plants (1886) offered some direct and telling strictures upon 

 Weismann's teachings (Chap. XXIII), and after the English 

 edition of the essays appeared he repeated these and answered 

 categorically a large number of points in a communication to 

 Nature* Professor Weismann replied to this review, defend 

 ing himself satisfactorily at some points, but was compelled to 

 recede from several of his most important positions. 



Mr. Patrick Geddes advanced in the Encyclopedia Britan- 

 nica (Art. Variation and Selection) a somewhat novel theory 

 of variation in plants, substantially in the same line, but prob 

 ably with some vulnerable points, and Professor Henslow's 

 recent work on the Origin of floral structures, seeks to show 

 that ' ' the responsive actions of the protoplasm in consequence 

 of the irritations set up by weights, pressures, thrusts, ten 

 sions, etc., of insect visitors," have played the principal role 

 in determining the forms of irregular flowers. In much of all 

 this there is a tendency to extremism, and harm is often done 

 by neglecting to recognize the action of natural selection where 

 it is clearly present, but there always remains a residuum of 

 facts which cannot be explained by that hypothesis. 



* Vol. XL, Oct. 24, 1889, p. 621. 



