2 THE OPEN COURT BIOLOGICAL SERIES. 



TH. EIMER 



Professor Eimer was the teacher of Professor Weismann 

 at Tuebingen. He has written vokuninons works and 

 his system has received much attention in Germany. 

 His theory is based mainly on the observation of 

 butterflies, while his famous disciple, Weismann, 

 relies chiefly on the generalization of facts derived 

 from the observation of ants. Although they re- 

 mained personal friends, they differ in their con- 

 clusions. 



The pamphlet On Orfhodenesis (i. e., evolution in a defi- 

 nitely determined direction) is a condensed statement 

 of his theory made by the professor's own hand, and 

 it acquires an additional zest by being a tilt at arms 

 directed against Weismann's Germinal Selection. (See 

 page 4.) 



On Orthogenesis (Definite Evolution) or the Impotence of 

 Darwinian Selection in the Formation of Species. By 

 Th. Eimer, Professor of Zoology in the University of 

 Tuebingen. Translated by Thomas J. McCormack. 

 19 cuts. Pp. 56. Paper 25c. (Is. 6d.) 



This little brochure was written in reply to Vv^'eismann's 

 "Germinal Selection." Prof. Eimer is a Neo-Lamarckian, 

 and his special doctrine of orthogenesis is declared to be a 

 universally valid law, framed to show that organisms develop 

 in definite directions, without regard for utility, through purely 

 physiological causes, through the transmission of acquired 

 characters, through the combined agency of the constitution of 

 the animal and the effects of outward influences. 



CARL VON NAEGELI 



Naegeli was the first to propose the general theory of cell- 

 formation as accepted today. His little brochure on 

 "A Mechanico-Physiological Theory of Organic Evo- 

 lution" is a synopsis of his great work on evolution 

 and will render his difficult theories accessible to 

 English-speaking students, to whom they have been 

 hitherto almost a sealed book. 



A Mechanico-Physiological Theory of Organic Evolution. 



Summary. By Carl von Xaegeli. Translated by \'. A. 

 Clark and F. A Waugh, of the University of Vermont. 

 The only original account of Naegeli's theories in 

 English. Pp., 52. Price, paper, L5 cents. (9d.j 



