No. 397-| REVIEWS OF RECENT LITERATURE. 55 
liquids from the foam, he has argued the necessary occurrence of 
many of the phenomena of cell division. On the same basis he now 
attempts to account for the distribution of pigment in many cases. 
With the aid of pressure experiments upon the yolk of the hen’s 
egg, the use of his system of elastic bands, and of the interesting 
gelatine models devised by Biitschli, the author endeavors to support 
an application of his views to the phenomena described by Fischel 
in 1899.  Fischel placed live eggs of echinoderms in very weak 
solutions of neutral red, and found that minute granules became 
stained all through the egg. When the egg divided, these granules 
were concentrated about the nucleus and in the spindle stage formed 
a dumbbell-shaped mass; later they were again more uniformly dis- 
tributed. Rhumbler endeavors to show that this apparent motion of 
the granules was not due to actual migration, and then explains it as 
a result of the drying effect postulated in his theory. If the nucleus 
absorbs water from the neighboring foam, the lamellz of that foam 
will become denser and the contents of the alveoli smaller, and large 
bodies, such as yolk spherules, be squeezed away from such a region 
of increased pressure. Small bodies may, however, remain, provided 
they have sufficient adhesion to the alveolar lamellae. This he assumes 
to be the case with the minute stained granules. In the region 
about the nucleus, where water is absorbed and from which large 
granules are forced away, there will be a condensation that must 
bring the granules nearer together if they stick to the shrinking 
lamella. The crowding of granules about the nucleus is thus due 
to a diminution in mass of material and not to a migration of gran- 
ules from afar. 
The author next takes up the arrangement of normal pigment in 
the eggs of Amphibia. The well-known dark streak that marks the 
path passed over by the sperm moving within the frog’s egg is due, 
he maintains, not to any attraction on the part of the sperm, nor to 
any manufacture of new pigment, nor to any other chemical process, 
but simply to the physical stress produced by the passage of a body 
through a foam. The sperm adheres to the foam framework and 
tends to pull it along; the resulting tension behind the sperm leads 
to outflow of the more liquid contents of the alveoli, and a shrinkage 
of the framework that draws the adherent pigment granules nearer 
together. 
The pigment is thus concentrated behind the sperm much as the 
colored granules were concentrated about the nucleus in Fischel’s 
experiments. The granules remain in the region of tension and 
