1895.] Embryology. ` 947 
Cell Phenomena in the Triton Egg.—Following in the steps 
of Driiner Dr. H. Braus of Jena, has made a careful study of cell 
division in the blastula stage of Triton alpestris. By special methods 
the achromatic spindles and polar radiations of cell division are 
brought out with great distinctness. In the spindle three kinds of 
. fibers may be present; delicate fibers that aid in moving the chromo- 
somes; fibers with a sheath, also pulling the chromosomes ; and stout 
fibers that connect the two centrosomes and serve as a supporting sys- 
tem tending to resist the pressure exerted by the other fibers. 
In the later blastula with several layers of cells just as in the gas- 
trula and in the adult testis as made out by Driiner, the arrangement 
of the fibers in the spindle is such that the contracting ones that act 
upon the chromosomes form the mantle or outer part, while the pres- 
sure-resisting fibers form the axial part of the spindle. . 
In the early blastula, however, cell division is different ; the spindle 
has its contracting fibers in the axial part and the resisting fibers in 
the outer part or mantle. 
The author comes to the conclusion that the more primitive form of 
spindle is that found in the older stages of the ontogeny of the Triton. 
© In the same way the author thinks that the origin of the spindle 
within the nucleus in the early stages of the development of the 
Triton’s egg is a ccenogenetic process, while its origin outside the 
nucleus, in the protoplasm of the cell, in the later stages and in the 
adult testis is really the more primitive method of spindle formation. 
In general the formation of a spindle within the nucleus is to be re- 
garded as a recent innovation, not as the original method. 
The very important question as to the reason for form in organisms, 
the laws of growth of organisms, receives a contribution from the 
author’s decision that the position of the spindles in the Triton’s blastu- 
læ (the angle which the axis of the spindle forms in successive cell 
divisions) does not necessitate the arrangement of the cells to form 
parts and organs. The author shows that the position of the spindles 
would not give rise to sets of cells placed as they are in the two-layered 
blastule if there were no rearrangements of the cells after division. It 
is change in position of cells after their formation and not forces in the 
processes of cell division that leads to the growth of form. 
In this Triton as many as nine sperms may enter one egg. These 
supernumerary sperms give rise, the author maintains, to certain extra 
nuclei recognizable even up to the blastula stage, so that the possibility 
of polyspermy having some lasting effect in the embryo receives some 
material basis. i 
® Jenaische Zeitschrift., May 15, 1895. 
