ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 539 



at the same stage of development. Thus all the structures which His 

 has described in the wall of the embryouic spinal cord can also be 

 recognised in the inner wall of the retinal cup, and may therefore 

 receive similar names. He goes on to describe the differentiation of 

 the myelospongial netwoik, &c, and the progress from day to day. 



Hofmann's Nuclei (Kblliker) in Spinal Cord of Chick.* — K. 

 Berliner proved independently of Kolliker and at the same time the 

 occurrence of segmentally arranged nerve-cell nuclei, appearing in the 

 ■earliest stages of development in organic connection with the spinal 

 cord of the chick, and retaining this connection throughout life. 



Branchial Clefts in Ophidia.f — A. Prenant and G. Saint-Eemy 

 find that three kinds of structures arise from the branchial clefts of 

 Cohiher sesculapii and Tropidonotus natrix. 



(1) There are solid buds produced bv a thickening of the wall of 

 a dorsal evagination, appearing transitorily in connection with clefts I., 

 II., and III., and possibly related to thymus elements. 



(2) There are hollow primordia produced by a development of the 

 whole nail of the cul-de-sac forming the base of the branchial pouch, 

 which in IV. and V. form a thymus properly so-called, while in III. 

 they form a homologous gland, quite different in structure from the 

 thymus. 



(3) There are hollow primordia arising from a email segment of the 

 median region of the fourth branchial p;>uch, forming little glands. 

 They are represented in rudimentary form in connection with pouch V. 



Pseudothyroid of Frog.} — H. N. Norris finds that the so-called 

 " ventraler Kiemenrest " of Maurer in the frog is not derived from any 

 part of the wall of the branchial chamber. It may be appropriately 

 described as " Pseuduthyreoidea " (Mayer). This pseudothyreoidea and 

 the corpus propericardiale have essentially the same structure, and 

 develop simultaneously. The arterial supply of the two is from the 

 same branch of the external carotid artery, the ramus musculo- glandu- 

 laris ; their chief venous outlet is the vena pseudothyreoidea. Both 

 originate in regions previously occupied by portions of the basihyo- 

 branchialis muscle of the tadpole. 



Eye-Muscles of Acanthias.§ — A. B. Lamb shows that the necessary 

 mechanical relations between eyeball and muscles are secured : — (1) by 

 a forward growth of processes from the second and third somites, and 

 the development of musch -fibres in them ; (2) by a spreading out of 

 the first somite around the eyeball and the development of muscles in 

 its distal portions. 



Evidence is adduced to show that the original direction of all the 

 eye-muscles is longitudinal, which seems to represent an originally 

 flexible condition of the head and to be an additional support for a 

 belief in the homology of head and trunk somites. 



* Anat. Anzeig., xxi. (1902) pp. 273-8 (1 pi.). 

 t Coniptes Rendus, exxxiv. (1902) pp. 614-6. 

 X Anat. Anzeig., xxi. (1902) pp. 434-42 (7 figs.). 



§ Tufts College Studies, No. 7 (1902) pp. 275-92 (9 figs.). ; Amer. Journ. Nat., 

 i. pp. 185-202. 



