1 Seem 
1897 | LIFE HISTORY OF LILIUM PHILADELPHICUM 443 
3 thinking that this will give any support to Weismann’s theory 
of heredity. It has been shown already by certain botanists 
that this theory breaks down entirely in the case of plants. 
Whether Strasburger’s theory of reduction is correct or not the 
future must decide. We are evidently not yet ready to estab- 
lish a theory of reduction, as we are dealing with phenomena 
concerning which hardly two observers agree. 
Nucleoli.— Apparently no structure in the cell is so little 
known as the nucleolus, and one needs only examine the litera- 
ture of the subject to discover how little has been done that can 
Stand the test of criticism. One of the most common ideas in 
regard to this body was that it represents a globule of food 
material which can be used by the nucleus or cell in general as 
occasion demands. Strasburger,? in 1895, suggested that the 
Substance of the nucleoli serves for the construction of the 
spindle threads, but it is doubtful whether there ever was any 
very strong evidence in favor of such a view. Went,’ in 1887, 
Saw in the endosperm nuclei that the nucleoli were lying in con- 
tact with the chromatin threads, and he thought the substance of 
the nucleoli was taken up by the chromosomes. It is very 
doubtful, however, whether any part of the nucleoli ever goes 
to aid in the formation of the chromosomes. Tangl? was the 
first to observe the extrusion of the nucleolus into the cyto- 
_ plasm. This was seen in the pollen mother cells of Hemerocallis 
fulva. Karsten attempted to show that the centrosomes had 
their origin in extruded nucleoli. It was soon shown by Guig- 
tard and others, however, that this was not the case, and that 
- Karsten did not see true centrosomes at all. Belajeff" has the 
‘Nucleoli passing out into the cytoplasm, but he claims that they 
are dissolved and that new ones arise in the daughter nuclei. 
7 Karyokinetische Probleme. Jahrb. f. wiss. Bot. 28: 151-204. 1895. 
* Beobachtungen iiber Kern- und Zelltheilung. Ber. d. d. bot. Ges. 5: 247. 1887. 
= Mec Kern- und a bei der Bildung des —s von Hemerocalits fulva L.. 
is, Aka 
