Pollen Mother-cells of Li Hum condidum , Linn . 289 
Hottes and Schrammen subjected various regions of the vegetative 
tissues of Vicia Faba to sudden changes in temperature ; subsequent 
examination of the parts thus treated revealed certain anomalous nuclear 
conditions comparable in many respects with those obtained by Miehe 
in Allium nutans. 
In 1905 Gregory (11) published a brief account of the cytology 
of a sterile race-hybrid of Lathyrus odoratus , in which a similar process 
was figured ( 1 . c., PI. II, Figs. 16 and 17). However, Gregory erroneously 
described this phenomenon as an incomplete or abnormal division by con¬ 
striction of the pollen mother-cells. He states further that such cells 
always degenerate, and that the sterility in these plants is confined to the 
male organs. 
According to Rosenberg ( 16 , 17 ), nuclear material is frequently 
pressed through the wall of a pollen mother-cell during synapsis, both 
in Crepis virens and in Drosera longifolia . No importance was attached to 
this phenomenon, which was thought to be the result of faulty fixation. 
A similar condition was observed in the pollen mother-cells of Vicia 
Faba by Fraser (8), who remarks ( 1 . c., p. 635) that the extruded ‘bodies ’ 
‘ seem clearly related to the incidence of an abnormal condition ’. 
This phenomenon has therefore in turn been regarded as : 
1. the result of an abnormal physiological condition of the anther at 
the time of fixation (Kornicke); 
2. an artifact (Rosenberg) ; 
3. a sign of the subsequent degeneration of the mother-cells concerned 
(Gregory, Fraser). 
There remains a fourth explanation, namely, that this process repre¬ 
sents a perfectly normal condition of the pollen mother-cell during synapsis. 
This, in our opinion, is the correct explanation, for there is certainly no 
evidence, at least in Lilium candidum, to indicate either that this condition 
is an artifact or that it foreshadows the degeneration of the mother-cells. 
Miss Digby found that after the nucleus had returned to the centre of 
the cell, the latter presented a perfectly healthy appearance (( 4 ) PI. XXXIV, 
Fig. 17), although the disintegrating fragments of the ‘ bodies ’ could still 
be identified in the cytoplasm as bright refractive granules. 
Moreover, Gates ( 10 ) ( 1 . c., p. 918) states distinctly that in Oenothera 
gigas ‘ the nuclei appear perfectly normal after the extrusion has taken 
place ’. 
The data now at our disposal are sufficient to justify the conclusion 
that future research will demonstrate the general occurrence throughout 
the Plant Kingdom of such an elimination of nuclear material as a normal 
phase in meiosis. It may represent an excretion of waste products from 
the nucleus at a time when its metabolism is subject to sudden profound 
changes. It is well known that the metabolic processes of the nucleus are 
U 
