614 Wisconsin Academy of Sciences, Arts, and Letters. 
same plant but makes no reference in bis paper to the contracted 
condition. Juel (46) figures the stage for Hieracium (Fig. 
52) and describes it as frequently following the homogeneous 
pachynema spirem, often forming a knot, “der jedoch mit der 
Synapsis wenig Aehnlichkeit hat.” Cardiff (14) says that he 
could find “no constant and definite stage that could be called 
a second contraction period” in the plants which he studied. 
Yet in his Figures 47 and 48 for Salmonia biflora he shows, 
in what he describes as “post-synaptic nuclei,” good representa¬ 
tions of the central tangle of the spirem, characteristic of the 
second contraction period. His figure 69 for Botrychium ob- 
liquum, although designated as a stage in recovery from synapsis, 
suggests very strongly a later prophase and represents well the 
appearance of the second contraction figure. 
In the heterotypic division in the formation of the germ 
cells in animals, a stage resembling the second contraction seems 
to be not uncommon. 
Eisen (20) describes and figures in the spermatogenesis of 
Batrachoseps, “the angular spirem stage” which has the gen¬ 
eral appearance of the second contraction figure and occurs in 
the prophase following a period of extended thick spirem. 
Janssens (48, 44) and Janssens and Dumez (45) describe 
the stage of “tension nucleaire” which they believe to be re¬ 
sponsible for the transverse segmentation of the spirem in late 
prophases. In the spermatogenesis of the Tritons, of Batrach¬ 
oseps attenuatus and Pletodon cinereus, this stage has been 
described as occurring in the late prophases after the longitudi¬ 
nal splitting has taken place. The loops formed at the time 
of the bouquet stage are described as extending away from the 
polar region by way of the periphery of the nucleus and return¬ 
ing by way of the interior. Attachment of the spirem to the 
nuclear membrane occurs at the polar region and in the regions 
where the loops extend along the periphery. When the spirem 
thread contracts it produces the stage of “tension nucleaire” 
which produces in the center of the nucleus “un noeud en partie 
inextricable” the nature of which in later stages becomes clear. 
Janssens believes that this stage of tension corresponds to the 
