146 whitman: [Vol. I. 



which my interpretation of the teloblasts is briefly noticed.^ 

 The same fact is more definitely stated in later papers (No. 20, 

 p. 4, and No. 21, p. 408). Bergh's interpretation of the neuro- 

 nephric stratum, as a neuro-epidermal layer, will be considered 

 after my own observations have been presented. 



For the latest contribution on the subject we are indebted to 

 Joseph Nusbaum (Nos. 8, 22, and 23). Nusbaum has given 

 a detailed account of the origin of the nerve-cord from the 

 epidermal layer, thus confirming the conclusion reached by 

 Kowalevsky and sustaining the position taken by Balfour (No. 

 12). Nusbaum is more fortunate in his company than in his ob- 

 servations, and this is almost the only reason that compels me to 

 burden the reader with a review of his statements. His elaborate 

 account of the mode of origin of the nerve-system from the 

 epidermal layer, in view of the fact that this layer has absolutely 

 nothing whatever to do with its formation, is, to say the least, a 

 most singular production, and one for which it would seem, at 

 first sight, very difficult to find any very satisfactory explanation. 

 But it undoubtedly has an explanation, and I am under the 

 disagreeable necessity of pointing it out. Nusbaum's observa- 

 tions, not only on the nerve-system, but on nearly every point 

 that he has discussed, show a most evident lack of thoroughness. 

 He has neglected to acquaint himself with the more important 

 facts in regard to the origin and structure of the germ-bands, and 

 the consequence is that he has misinterpreted and blundered at 

 nearly every step. He has just as little knowledge of the anatomy 

 as of the embryology of Clepsine ; for he starts out under the 

 persuasion that there is only one pair of testicular sacs, (No. 

 22, p. 614). And yet these sacs are so large and conspicuous 



* In justice to Bergh it should be stated that his remarks on the origin of the nerve-cord 

 are intended only to serve as a preliminary account. 



(20.) Bergh, R. S. Uber die Deutung der allgemeinen Anlagen am Ei der 

 Clepsinen. Zool. Anz. No. 2l6. 1886. 



(21.) Id. — Die Entwicklungsgeschichte der Anneliden. Kosmos. II. p. 401 

 i886. 



(8.) Nusbaum, Joseph. Recherches sur TOrganogenese des Hirudinees (Clepsine 

 complanata Sav.). 



Arch. Slaves de Biologie. I. fasc. 2, pp. 320-340; fasc. pp. 539-556. 1886. 

 (22.) Id. — Zur Entwicklungsgeschichte der Hirudineen (Clepsine). 



Zool. Anz. VII., No. 181, p. 609. Nov., I884. 

 (23.) Id. — Zur Entwicklungsgeschichte der Geschlechtsorgane der Hirudineen, 

 Zool. Anz. VIII., No. 191, p. i8i. Mar., 1885. 



