276 Dixon . — The Possible Fttnction of 
nuclear membrane. I11 all probability, as Humphrey and 
Strasburger 1 have pointed out, this body is formed as a pre- 
cipitate from the nuclear fluid. Zimmermann 2 has shown 
that its substance is derived from the nucleolus. In fact the 
attenuated chromatin-thread is at this stage immersed in 
a nuclear fluid containing an exceedingly large amount of 
nucleolar substance suspended 3 in it ; and we may regard the 
elongation of the thread and this synaptic stage as a process 
for distributing all the i dioblasts or bearers of the hereditary 
properties with great uniformity along the chromatin-thread, 
so that the nuclei of the reproductive cells which arise from 
the nucleus under consideration may be all equally possessed 
of these properties. The undisintegrated or persisting portion 
of the nucleolus of this nucleus, being fragmented and extruded 
in the karyokinesis immediately following this stage, most 
probably contains that portion of the hereditary mass which 
is to be got rid of, and which is not to appear in the succeeding 
generation nor again in the phylogeny of the species. 
The behaviour of the sexual nuclei during fertilization also 
indicates the hereditary function of the nucleolus,- and it would 
appear that if we attribute hereditary properties to the 
chromatin of nuclei there are observations which compel us 
logically to assign these properties to the nucleolus also. 
Thus not infrequently in the higher plants, both the male and 
female nuclei contribute nucleolar matter to the nucleus of the 
oospore 4 . The most striking observation in this respect is, 
however, that which has been made on the fertilization of 
Fucus by Farmer and Williams and by Strasburger 5 . In this 
Alga the sperm-nucleus is very rich in chromatin before 
fusion with the nucleus of the ovum, and no nucleolus is 
1 Humphrey, Nukleolen u. Centrosomen; Ber. d. D. Bot, Ges., 1894, p. 108. 
2 Zimmermann, Morph. 11. Phys. d. pflanz. Zellkernes, p. 69. 
3 According to the view here urged the solution of the nucleolus does not take 
place, but rather its subdivision into idioblasts, which may be supposed to be 
suspended in the nuclear fluid after the disappearance of the nucleolus. 
* Guignard, Nouv. Et. s. 1. Fee., Figs. 8o, 81. 
5 Farmer and Williams, Fertilization of Fucus ; Phil. Trans. B., 1898, Figs. 20, 
21. Strasburger, Jahrb. f. wiss. Bot., xxx; Taf. xviii, pp. 246, 267, 286. 
