ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
Ill 
I. Primary Type. 
Archi-holobastic — Amphioxus. 
Proto-holoblastic — Eggs that have never acquired a large 
yolk-mass, and hence have retained the primary condition 
nearest to Amphioxus — Cyclostomi. 
Proto-mesoblastic. 
(a) Eggs that have acquired a large primary yolk-mass — 
Elasmobranchii. 
( h ) Eggs that, having lost the large primary yolk-mass, 
have retained the mesoblastic mode of segmentation 
— Teleostei. 
Meso-holoblastic. — Eggs that had a large yolk-mass, but have 
returned to the holoblastic condition — Amphibia (?). 
II. Secondary Type. 
Meta-mesoblastic. — Eggs that, having had a large primary yolk- 
mass, have lost it and now reacquired it — Reptilia, Aves. 
Meta-lioloblastic. — Eggs that have passed through the pre- 
ceding stage, but again lost the yolk-mass, and returned to 
the holoblastic mode of segmentation — Mammalia. 
Reproduction and Development of the Common Eel.* — Prof. G. B. 
Grassi has made a series of most interesting observations on the life- 
history of Anguillula vulgaris. Four years of continuous research have 
enabled him to dispel the great mystery which has hitherto surrounded 
the reproduction and development of this common fish. That which has 
hitherto been known as Leptocephalus hrevirostris is the larva of the eel. 
The eel spawns in the sea, and the eggs float ; maturity is reached 
in the depths of the sea. 
Herr K. Knauthe f remarks that light is beginning to dawn on the 
“ eel-question,” and that it might soon be clear if the zoologist would 
make friends with the fisherman. In 1894, Herr A. Feddersen declared 
that the broad-nosed eel was resident and capable of reproduction in 
Swedish lakes. Herr Knauthe maintains that the same may be said for 
Brandenburg and elsewhere. He regards the land journeys of May and 
June as certainly reproductive in aim, and cites some cases which it 
seems difficult to interpret, except on the theory that reproduction may 
occur in fresh water. 
Life-Histories of British Fishes.J — Prof. W. C. MTntosh treats of 
the spawning of the lesser sand-eel, the eggs and young of the Pollack, 
the life-history of the Lumpsucker, the eggs and young of the bimacu- 
lated Sucker, and the life-history of Cottus scorpio. A number of useful 
details are given, but there are no generalisations of any kind. Essen- 
tially the same results are reported on elsewhere.§ 
£. Histolog-y. 
The Cell in Development and Inheritance. || — We cannot do more 
than call attention to this work by Prof. E. B. Wilson. The author 
* Quart. Journ. Micr. Sci., xxxix. (1896) pp. 371-85 (4 figs.). 
t Biol. Centralbl., xvi. (1896) pp. 847-8. 
% Ann. and Mag. Nat. Hist., xix. (1897) pp. 241-61. 
§ 14th Annual Kep. Fishery Board for Scotland, pt. iii. pp. 171-85 (1 pi.). 
j| New York and London, 1896, 8vo, xvi. and 371 pp., 142 figs, in text. 
