ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 467 
of the nucleolus. At the time of the formation of the second spindle 
it had entirely disappeared. 
Centrosome and Fertilisation.* — M. Felix Le Dantec has a brief 
note on this subject. He believes that the reaction which followed 
the disproof of Fol’s “ quadrille of the centres,” has induced embryo- 
logists too hastily to accept the position of Boveri that the centrosome 
of the fertilised egg is that introduced by the sperm. If centrosome 
be defined as a specialised portion of protoplasm within an aster, then 
the centrosome is absent alike from mature ovum and from sperm. If, 
on the other hand, the word be used to designate a portion of proto- 
plasm capable of producing an aster, then, although such specialised 
protoplasm can be demonstrated only in the sperm, may it not exist in 
diffuse condition also in the ovum ? The phenomenon of fertilisation 
might then be explained in the following way. The sperm, in addition 
to the male pronucleus, contains a mass of male protoplasm (the so- 
called centrosome or spermocentre), while the ovum contains diffuse 
female protoplasm (diffuse centrosome or ovocentre) in addition to the 
female pronucleus. The male protoplasm exercises upon the female 
an attraction similar to that which the nuclei exercise upon one another, 
and round the two the aster forms (centrosome of fertilised egg). Thus 
there is a protoplasmic fertilisation as well as a nuclear one. This 
suggestion is in essence similar to Fol’s theory apart from the appear- 
ance described by him, and the author believes that it is not only in 
as perfect harmony with the facts of observation as that of Boveri, but 
that it explains Delage’s experiments on the fertilisation of non- 
nucleated eggs. 
Centrosome and Periplast. f — Professors Vejdovsky and Mrazek 
publish a preliminary note on their researches on this subject. The 
former author, in his observations on the process of fertilisation carried 
on twelve years ago, used eggs of Bhynchelmis , which he regards as 
exceptionally favourable material. Until quite recently he has been 
unable to procure more material ; but, having succeeded, he now finds 
that his results, in spite of new methods, are the same as his previous 
ones. The authors find that centrosome and periplast (attraction-sphere) 
are constant organs of the cell, and that the centrosome always lies 
within the periplast. The periplast of the next division arises endo- 
genously within the previous sphere. The rays also are new formations 
arising from the reticulum of the previous periplast. As to the origin 
of the periplast, the authors think there is no doubt that it arises from 
the specialised cytoplasm contained in the middle piece of the sperm. 
Structure and Development of the Spermatozoa in the Guinea- 
pig.! — Dr. F. Meves has made a very exhaustive series of observations 
on this subject. He finds that after the last maturation division, the 
spermatides contain a large central nucleus, an idiozome or sphere con- 
taining numerous corpuscles staining darkly with iron-hsematoxylin, 
two central corpuscles outside the sphere, and finally some chromatoid 
bodies showing the staining reactions of nucleoli. During the first 
* Comptes Rendus, cxxviii. (1899) pp. 1341-3. 
f SB. Bohmisch. Ges., 1898, pp. 3-11 (6 figs.). 
% Arch. Mikr. Anat., liv. (1899) pp. 329-402 (3 pis. and 16 figs.). 
