ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
685 
the development of the reproductive organs, and in the time at which the 
elements differentiate. Their first appearance remains unknown. There 
are interesting nuclear changes in the spermatogonia ; without kinetic 
division the nuclear threads fall into four chromosomes, and each of 
these forms a now nucleus. It seems that the germinal epithelium is at 
first confined to small organs, and that the voluminous tubes (“ sperm- 
sacs,” not “ testes ”) are secondary. So in the female, the original tubes 
with germinal epithelium give rise, by lateral paired evaginations, to the 
long uterine tubes, into which the ripe eggs of the adult return. But 
these are only a few of the results which Vejdovsky has reached. 
Muscular Cells of Ascaris.* — MM. G. Gilson and J. Fantel describe 
a prerectal sphincter muscle in Ascaris which is remarkable for being 
unicellular ; the cell has the form of a closed ring, and the protoplasmic 
contents are only very incompletely differentiated into muscular sub- 
stance ; externally there is a layer of non-differentiated protoplasm, in 
which lies the nucleus. The musculature antagonistic to the sphincter, 
varies a little in different species ; in A. megalocephala two cells, remark- 
able for the prolongations by which they come into manifold relations 
with neighbouring organs, function as dilatator muscles of the intestine, 
and as elevators of the pad which projects into the rectum. The whole 
forms an irregular ring, whence a number of prolongations are given off, 
most of which are more or less radial in direction. As the authors can 
find only two nuclei in this complex system, they are led to consider 
that it is made of only two cells. 
The powerful musculature of the ejaculatory canal is formed by pro- 
longations sent out by the “ bursal fibres ” of a definite region. These 
anastomosing prolongations are undoubtedly muscular in nature. 
Helminthological Hotes.f — Dr. A. Mueller begins with an account 
of Filaria ( Spiroptera ) gastrophila sp. n. (?) found projecting from the 
walls of a cat’s stomach ; this would appear to be the first Filaria found 
in a cat. Strong yluris brevicaudata sp. n. from a West African Lizard 
( Agama colonum ) would appear to be a new generic type, allied to 
Oxyuris and Leptodera on the one hand and to Strongylus on the other. 
EchinorJiynchus pristis and E. annulatus have been found in species of 
Exoccetus ; and Distoma segmentatum is a new species from the small in- 
testine of Vidua paradisea. Several partly known species are also 
described. 
y. Platylielminthes. 
Asexual Reproduction in Freshwater Turbellaria.f — Herr J. 
Keller has made a study of various Turbellaria, in which he finds that 
the mode of asexual reproduction is of the kind called paratomy, or 
division accompanied by the formation of organs ; there is no budding 
in this class. The various forms of asexual reproduction in it may be 
classified thus : 
a. Paratomy with regeneration of complete parts of the body ; 
(1) With deferred formation of organs, e. g. Planaria atbissima. 
(2) With simultaneous formation of organs, 
e. g. Planaria subtentaculata. 
* Anat. Anzeig., ix. (1894) pp. 724-7 (2 figs.). 
f Arch. f. Naturg., lx. (1894) pp. 113-28 (1 pi.). 
X Jenaische Zeitschr., xxviii. (1894) pp. 370-407 (4 pis.). 
