562 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Embryo of Chlamydoselachus anguineus.* — H. E. Ziegler describes 

 three embryos of this interesting Japanese Selachian, which measured 

 25 and 75 mm. He discusses " Seesel's pouch " and " Ratke's pouch," 

 the pre-mandibular and mandibular cavities in the head, and the crania] 

 nerves. 



Study of Heredity.f — M. Nussbaum gives a sketch of the great 

 steps of cytological inquiry in regard to heredity, from his own state- 

 ment in 1879 of the general idea of germinal continuity to the recent 

 work of Wilson and others. 



b. Histology. 



Bipolarity of Cell-division.} — Angel Gallardo re-states his dynam- 

 ical interpretation of cell-division. Typical division depends on the in- 

 tense positive polarisation of the centrosomes, followed by the intense 

 negative polarisation of the chromatin. The gametes are unipolar ; their 

 union restores the bipolarity which is an essential condition of cell- 

 division. 



Mitochondria of Seminal Epithelium of Rat.§— CI. Regaud finds 

 that mitochondria are not fixed parts of the cytoplasm. They change 

 with the functioning of the cell. They are not permanent elements of 

 the nutritive syncytium, and are evidently connected in some way with 

 the development of the spermatozoa in the seminal epithelium. 



Intestinal Musculature in Tench. || — E. Retterer and A. Lelievre 

 describe in detail the smooth muscle of the muscularis mucosa? and the 

 striped muscle of the muscular tunic. Iu both cases the muscular 

 elements show a reticulum (strongly stainable with hematoxylin), and a 

 hyaloplasm (selecting alum-carmin). There is a fundamental resem- 

 blance between the two types of muscular element, but a difference of 

 arrangement. 



Thyroid and Parathyroid.^" — J. Halpenny and F. D. Thompson 

 have published four sections which go to show the intimate morpho- 

 logical relationship between thyroids and parathyroids. After removal 

 of the thyroid from a dog, the external parathyroids were to all intents 

 and purposes converted into thyroid. The most noticeable feature about 

 the thyroid tissue which has developed from parathyroid is the irregular 

 shape of the vesicles, but the appearance thus presented is strikingly 

 similar to that which is found in the thyroid gland after para- 

 thyroidectomy. 



Structure of Afferent and Efferent Arteries of the Renal Glo- 

 merulus in Mammals.** — G. Vastarini Cresi finds that the afferent and 

 efferent artery of the renal glomerulus differ in structure. The walls of 



* Anat. Anzeig., xxxiii. (1908) pp. 561-74 (7 figs.). 

 f SB. Nat. Ver. Preuss Rheinlaud, 1909, pp. 13-25. 

 % Revista Mus. La Plata, xvi. (1909) pp. 7-31. 

 § C.R. Soc. Biol. Paris, lxv. (1908) pp. 566-8. 

 11 Op. cit., lxvi. (1909) p. 571-4. 

 i Anat. Anzeig., xxxiv. (1909) pp. 376-9 (4 figs.). 

 ** Tom. cit., pp. 94-105 (1 fig.). 



