304 Beer, Development of tlie pollen grain and antlier of sonie Onagraceae. 
Tliis continuons nnclear mnltiplication, by botb direct and 
indirect division, must lead to tbe accumulation of a large num- 
ber of nuclei in eacb cell unless an opposite process, reducing 
tbeir number takes place at tbe same time. . 
An glance at a section of an older antber will at once 
sbow tbat no excessive accumulation of nuclei occurs in tbe cell 
and I bave succeeded in bnding clear evidence of a nuclear de- 
generation taking place side by side witb tbe nuclear multipb- 
cation. 
In tliis process tbe nuclear membrane, wbicb stains very 
deeply, becomes ruptm*ed and sliredded out into a group of fibres 
or narrow laminae wbilst tbe nucleolus can also, in many in- 
stances, be seen to resolve itself into a coarse fibre. 
Tliere can be little doubt tbat tlie groups of fibres formed 
in tliis manner correspond to tbe structures wliicb Meves 1 ) bas 
recently described in tbe tapetal cells of Nymphaea alba and 
wbicb be bas compared to tbe cliondromiten of certain animal 
cells. 
It is quite easy, in well fixed material, 2 ) to find all stages 
between a complete nucleus and one tbat is only represented by 
a group of fibres. In Fig. 43, 44 and 45 d and f I bave drawn 
nuclei wbicb are degenerating in tliis way. 
Tliese fibres, of nuclear origen, become gradually more 
numerous in older antbers, as tlie tapetal nuclei continue to di- 
vide and to degenerate, but wlietlier tliey all persist as fibres or 
wbether some of tliein are lost sigbt of in tbe course of furtlier 
cbanges I am unable to say. It is certain, bowever, tbat tbe 
cytoplasm of tbe tapetal cells wbicb are approacbing disintegration 
stains very deeply and tbat it contains a large number of tliese fibres. 
Just before tapetal disintegration tlie wbole contents of tbe 
cell, apart front tbe unaltered nuclei, 3 ) break down into coarse 
granules wbicb stain intensely witb iron-baematoxylin and tliese 
become distributed arnong tbe pollen grains wben tbe cell loses 
its individuality. 
Düring tlie development of tlie antlier starcli appears and 
again disappears in tlie tapetum according to tbe conditions of 
growtli and tliis sbows tbat carbobydrates are being emploved 
in metabolism. 
Tbe conclusion wbicb may be drawn front tbe above facts 
t 
is tbat a large part of tlie material wliicb accumulates in tbe 
tapetal cells during tbeir development and wbicb subsequently 
passes into tlie pollen grains to replenisb tbeir exliausted proto- 
plasts bas at one time or anotlier entered into tbe composition 
of tlie tapetal nuclei und tbat tliere is bere, tberefore, a direct 
relation between nuclear substance and cytoplasmic growtb. 
!) Meves, Fr. „Über das Vorkommen von Mitocliondrien bezw. Clion- 
dromiten in Pflanzenzellen.“ (Bericlite d. Deutsch., bot. Glese]l. XXII 1904. 
pp. 284—286.) 
2 ) Wor cester’s fluid is by far tlie best fixatine for tliis pnrpose. 
3 ) AYliicli are two or tliree in number. 
