1904] CURRENT LITERATURE 397 
threads of the central portion of the spindle which may become imprisoned. No 
karyoplasm is formed in the nucleus of Trillium. In passing through the telo- 
phase to the resting condition, no continuous spirem is formed. 
Prophase in root tips. The nuclear network becomes resolved into alveolar 
or reticular pieces. A process of concentration and homogenization (sit venia 
wrbo) continues until the chromosomes have the form of homogeneous rods. 
There is no continuous spirem in the prophase and the chromosomes never present 
the form of an achromatic ribbon carrying chromatic granules. The longitudinal 
division of the chromosomes begins by the formation of a series of chinks lying 
along its axis and not by the division of granules. In the nuclear cavity there 
are no granular or filamentous structures, but only the chromatin (and nucleolus) 
lying in the nuclear sap. 
Telophase oj second division in pollen mother-cells. No daughter thread is 
lomed. The nucleus results from the confluence of one or more vesicles each 
of which contains one or more chromosomes. A chromatic vesicle in Trillium 
8a vacuole containing a chromosome bathed in nuclear sap. The nuclear mem- — 
brane is formed by the condensation of the peripheral layer of cytoplasm bordering 
the nuclear vacuole. 
The writers define the nucleus (excepting nucleoli) about as follows: In 
Trillium the nucleus is a vacuole limited by a cytoplasmic membrane, filled with a 
nuclear sap in which lies a chromatic network consisting of a homogeneous ground 
substance, without differentiation into an achromatic substratum and chromatic 
the 2 The network, which arises from the juxtaposition of the networks of 
vidual chromosomes, apparently retains its composite character during 
= ei and so might be defined as an association of chromosomes 
ome alveolar and reticular.—CHARLES J. CHAMBERLAIN. 
; STRASBURGER?9 in 
"ews which are 
to be no ground for interpreting the second division as a 
Rvorable, since i+ Galtonia candicans, the principal form studied, is particularly 
~ “8 tt has only six chromosomes and is easy to stain. In the pollen 
longitudinal ‘ “ 8 the loose spirem stage of the first division the thread shows a 
becomes —. mang, but the daughter threads do not separate. The thread 
*hich are bivale: thicker, and simpler, and then divides into six chromosomes 
arise a as shown by the fact that each one splits transversely into two. 
SaPes 50 often a mons united in pairs. The pairs assume the various 
id are nearin tved. After the two parts of each pair have become separated 
Sthe longitudi Poles of the spindle, a longitudinal fission can be seen. This 
Te hal fission commenced but not completed in the loose spirem stage. 
——_2s become placed end to end, but are united only by linin threads, 
* StRasp 
Akad. Wy: URGER, Epuarp 
iss. 18. , Ueber Reduktionsteilung. Sitzungsb. Konig]. Preuss. 
* 587-61 tee 
4. figs. 9 
