ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 541 



Precocious Sexual Development.* — W. Roger Williams has pub- 

 lished a careful essay on developmental anomalies of this kind, with 

 abstracts of over one hundred authentic cases. His classification for 

 females runs : — I. Precocious sexual development, (a) at birth or there- 

 abouts, (fe) birth to the sixth month, (c) sixth month to one year, (d) 

 one to two years, (e) two to three years, (/) three to four years, and so 

 on to seven years — altogether 59 cases; II. Precocious sexual develop- 

 ment with concomitant intra-abdominal tumour (13 cases); III. Pre- 

 cocious pregnancy, 15 cases, at 8, 9, 10, 11, 12, 13 years. Then follow 

 20 cases of precocious sexual development in males, e.g. of boys who 

 were parents at 13 years and 3 months and at 14 years, " believed to be 

 the earliest examples of precocious paternity extant." 



Recent Teratological Work.f — B. C. A. W indie has issued the 

 twelfth of his valuable reports on recent teratological investigations, 

 arranged under the heads, — (1) experimental, (2) general, (3) duplicity, 

 (4) various parts of the body. 



b. Histology. 



Studies on the Retina.! — H. M. Bernard discusses in the third 

 part of his studies on the retina the migration of the retinal nuclei. 

 The fourth part is devoted to the vesicular swellings at the tips of the 

 " cones," and some earlier form-phases in rod-production in the Am- 

 phibians. The fifth part discusses the removal of the absorbed pig- 

 mentary matter from the rods, — an explanation of " Midler's fibres." 



The conclusion which of all others now arrived at is of widest 

 significance from a general poiut of view, is that the retina can no 

 longer be regarded as built up of so many separate " cells," each with 

 some definite and permanent morphological value. The functional 

 retina is really a continuous cytoplasmic reticulum in which nuclei are 

 suspended, and these nuclei are not stationary. With reference to the 

 retina itself as the specific organ of vision, by far the most important 

 result obtained by the author is the discovery of some new details 

 relating to the origin and structure of the rods, that is, of those struc- 

 tures which are peculiar to the retina as the visual organ. The parallel 

 between the rods and cuticular formations does not work o.ut ; the 

 "cones" are not always analogous structmes ; the striation of the rods 

 is due to strands in the walls of the rod-vesicles; the refractive matter 

 which fills the outer limbs of the rods is^absorbed pigment, which is 

 usually, but not always, clarified during the process of absorption ; 

 Miiller's fibres are merely streams of the pigment matter which have 

 been absorbed by the rods, and which pass inwards through the retina, 

 eventually to join the vitreous humour. 



Retina of Hatteria.§ — Hs. Virchow has been able to make a satis- 

 factory study of well-preserved retinae, and although he has found 

 nothing essentially different from what occurs in the retinse of other 

 Reptiles, there is interesting evidence of detailed differentiating pecu- 

 liarities. 



* Brit. Gynaecol. Journ., Mav 1902, pp. 85-114. 



t Journ. Anat. Physiol., xxxvi. (1902) pp. 296-308. 



J Quart. Journ. Micr. Sci., xlvi. (1902) pp. 27-75 (3 pis ). 



§ SB Ges. Nat. Freunde Berlin, 1901, pp. 42-62. 



October loth, 1902 2 o 



