ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 467 



dorsal and two ventral, but ganglia are not differentiated. In the pos- 

 terior neck region where the proglottides begin to appear, ganglionic 

 swellings appear on the lateral nerves. In a mature proglottis acces- 

 sory longitudinal nerves appear in addition to the six described ; the 

 lateral trunks show an anterior and a posterior ganglion at each side, 

 and the dorsal and ventral nerves also display ganglionic swellings. The 

 paper is illustrated by some very clear figures. 



Development of Cestodes.* — G. Saint Eemy briefly describes the 

 development of Anoplocephala plicata Zeder and A. mamillana Mehlis, 

 parasites of the horse. The spherical ovum has a very delicate envelope 

 and a large mass of almost homogeneous yolk. What looked like two 

 polar bodies were seen. Some of the early blastomeres increase greatly 

 in size, as if at the expense of the yolk. Two of thein penetrate into 

 the yolk, which then fragments. The two cells end by surrounding the 

 other elements of the ovum and forming an external envelope. Mean- 

 while, three large cells form an internal envelope surrounding numerous 

 small elements without distinct boundaries. In short, the development 

 is very like that in Bothriocephalus and Taenia serrata. No diploblastic 

 arrangement, however, was observed. 



Cestodes of Birds.f — Dr. L. Cohn publishes the first of a series of 

 papers on the anatomy and systematic position of the Cestodes of birds. 

 The present paper discusses the structure of the following species : — 

 Amdbilia lamelligera Owen, Schistotaenia scolopendra Diesing, Sch. macro- 

 rhyncha Eud., Taenia polymorpha Eud. ex parte. 



Development of Echinococcus Scolices. $ — Herr E. Goldschmidt 

 notes the discrepancies which exist in the literature in regard to this 

 subject. His own observations seem to him not only to reconcile the 

 apparently discordant statements of other authors, but also to shed light 

 on the development and significance of the rostellum. The first trace 

 of the scolex is a disc-like thickening of the wall of the brood capsule. 

 This gradually rises up to form a button, while a circular furrow appears 

 at the same time around its base. The furrow deepens into a pit, within 

 which lies the dome-shaped projection, the two constituting the hollow 

 bud (Hohlknospe) of Leuckart. The central projection is the rudiment 

 of the rostellum, and projection and pit together are the homologue 

 of the Kopfzapfen of a Cysticercus, the only notable difference being 

 the early appearance of the rostellar region in the former case. Later 

 there begins that process of differential growth which was interpreted 

 by Leuckart as invagination. Details of the development are given ; 

 but the chief point of general interest is in regard to homology. The 

 fully formed scolex of an Echinococcus exhibits a strong resemblance to 

 the Cysticercoid of Taenia cucumerina ; but this resemblance must never- 

 theless be looked on as secondary and adaptive only, for development 

 shows that the Echinococcus scolex is the homologue of the Kopfzapfen 

 of Cysticercus. 



In regard to the phylogenetic significance of the rostellum, the 

 author considers that his observations lend no support to the theory 



* Comptea Rendus, exxx. (1900) pp. 930-2. 



t Zeitschr. wiss. Zool., lxvii. (1900) \>p. 255-90 (2 pis.). 



j Zool. Jahrb. (Abt. Anat.), xiii. (1900) pp. 467-94 (1 pi. and 1 fig.). 



