40 
8UMMARY OF CURRENT RESEARCHES RELATING TO 
nuclear substance is very much smaller than in the Mammalian egg. 
The egg of Amphioxus is much more like that of Amphibians and 
Lampreys. The just evacuated egg has a structureless envelope directly 
touching the delicate outer zone of protoplasm. It contains one radially 
placed directive spindle, which is formed in the ovary directly before 
the evacuation of the eggs. At the pole of the egg at which the directive 
spindle lies there is a small quantity of protoplasm which is free or 
almost free of yolk-granules. Immediately after the deposition of the 
egg, which ordinarily occurs in water in which spermatozoa have 
already been evacuated, one or more spermatozoa make their way into it. 
The author describes the disappearance of the directive spindle, and the 
formation of the male and female pronuclei. These gradually approach 
one another, and, uniting, fuse to form the first cleavage nucleus. The 
first cleavage is effected very slowly, and some time after the formation 
of the daughter-nuclei. The yolk is not divided into two distinct 
halves. Like Hatschek, the author noticed that after division was 
completed there remained for a long time between the two spheres a 
bridge of protoplasm which was poor in yolk. 
New Species of Viviparous Fish.* — Dr. A. Alcock describes a new 
species of Diplcicanthopoma. He finds that there is no attachment or 
adhesion of any kind between the ovarian capsule and its conteuts. The 
embryos form a thick surface layer immediately beneath the capsule, 
and enclose a central mass of largish ova, which consist entirely of yolk- 
spherules, without any trace of an embryo or even of a germinal area. 
These latter are probably intended for present use rather than for a 
future brood. The embryos, which are long and eel-like, lie matted 
together, and firmly adhering to one another by means of a coagulated 
secretion. The vertical fins only are represented by a long fold of in- 
tegument, which consists of layer upon layer of large nucleated cells. 
The author is inclined to think that this fold, which is really only an 
extended sheet of embryonic cells, is an absorbent surface. It differs 
however, from that seen in the embryos of certain fishes of the family 
Embiotocidse in that there is no vascular connection, at any rate on the 
fcetal side. The author thinks that the nutrient material is absorbed 
not so much from the thin tough ovarian capsule as from the ovary, in 
which no trace of a germinal vesicle can be found. 
Phenomena of Reproduction.* — The full title of Dr. J. Beard’s 
paper is, ‘ On the Phenomena of Reproduction in Animals and Plants, on 
Antithetic Alternation of Generations, and on the Conjugation of the 
Infusoria.’ The final result of these essays is to show that there is one 
universal law underlying all the processes of conjugation and fertilisa- 
tion which are classed together as sexual in nature. Dr. Beard appears 
to have been drawn to the considerations, which he puts forth in this 
paper, by an article by Strasburger on the periodic reproduction of the 
chromosomes in living organisms. Zoologists in general, having as 
little belief in the occurrence of spore-formation in animals, as in anti- 
thetic alternations in generations, and being limited by a blind acceptance 
of recapitulation with direct development, or by a simple negation of any 
* Ann. and Mag. Nat. Hist., xvi. (1895) pp. 144-6. 
I Anat. Anzeig., xi. (1895) pp. 234-55 (5 figs.). 
