328 
Wager. — On the Presence of 
of Ascaris megalocephala , var. univalens as being nuclear in 
origin. His figures are certainly very clear and show the 
centrospheres distinctly inside the nucleus. The division of 
the centrospheres into two and the formation of the spindle- 
figure may all take place within the nucleus, but these bodies 
are finally extruded through gaps in the nuclear membrane 
into the cytoplasm, where they become surrounded by radiating 
striae. In some cases, even, the centrospheres may pass to 
the outside before dividing. The author regards both centro- 
spheres and spindle-figure as nuclear in origin. 
O. Hertwig 1 also states that the centrospheres belong to 
the resting nucleus and only come out into the cytoplasm for 
division, and it is only in special cases that the centrosphere 
remains in the cytoplasm during the resting stage of the 
nucleus. 
Hausemann 2 , from observation on cells in pathological 
tissues, also supports this view. 
Strasburger 3 summarises the various cases of centrosphere- 
and spindle-formation somewhat as follows : — 
(1) The centrosphere is found inside the nucleus, and the 
whole of the nuclear spindle is formed from the contents of the 
nucleus. 
(2) The centrosphere lies outside the nucleus, but the 
spindle owes its origin to a substance which is formed in 
the nucleus. 
(3) The spindle is formed partly from a substance in the 
cytoplasm, and partly from a substance in the nucleus. 
(4) The spindle is formed out of a substance which only 
occurs in the cytoplasm. This is universal for plant-cells. 
Moore 4 has recently shown that in the reproductive elements 
of Apns and Brachipus the centrospheres are derived from 
a massing together of a number of deeply stained bodies, 
which he calls pseudosomes, found in the angular spaces in 
a network of protoplasm exterior to the nucleus ; and Farmer 5 
1 Die Zelle und die Gewebe, 1893. 2 Anat. Anzeiger, VIII, 1892. 
3 Ueber die Wirkungssphare, &c., Hist. Beitr. V, 1893. 
4 Q. J. M. S., 1893, 5 Annals of Botany, Vol. VII, 1893. 
