McAllister—-Cytology and Embryology. 609 
On the other hand Miss Sargent (83), Overton (73), Berghs 
(5), and Schleip (88) have reported synapsis as distinguish¬ 
able in living cells. Schleip figures this stage from living ma¬ 
terial. 
Schaffner (84, 85, 86) is of the opinion that the synaptic 
knot is an artefact due to fixation. In hisi recent work on 
Agave (86) he reports that in living pollen mother cells no 
trace of synaptic contraction is to be found. 
McClnug’s (51, 52) work on the insects has also led him to 
the conclusion that the synaptic contraction is an artefact. 
Mottier (65) has regarded the synaptic knot as due to fixa¬ 
tion and in a recent paper (67) has offered evidence to that 
effect. He has fixed, embryo-sac mother cells of Lilium, some 
with the nucellar tissue intact and others with the tissue cut 
away so as to bring the mother cell close to the surface. In 
the untrimmed ovules he figures formless masses at the time 
of synapsis and in the trimmed ovules a fine spirem may be 
seen. His results thus suggest that the dense, contracted masses 
are due to fixation. It would seem that embryo-sac mother 
cells were not favorable for such a comparative study as this 
because of their isolation one from the other. In the Lily 
anther several mother cells may easily be brought into direct 
contact with the fixative by cutting, while those deeper will be 
less exposed. These large anthers have been more frequently 
studied than those of any other genus, and all accounts agree 
that synapsis is here entirely independent of proximity to cut 
surfaces in fixation. 
Janssens (44) believes that in the spermatogenesis of Batrach- 
oseps the characteristic synaptic figure is found only in those 
cases in which the fixation is poor. He finds that commonly 
the peripheral spermatogonial nuclei of a testis show no well 
defined synaptic contraction while in the deeper lying nuclei 
contraction is conspicuous. 
Berghs (6) is inclined to believe that the synaptic contrac¬ 
tion occurs normally though it is accentuated by the action of 
the fixing agent, and in this respect Lerat (49) is practically in 
accordance with him. 
