APPENDIX. 
BOOK I. 
Page 8. Cell-formation by Rejuvenescence. In most cases the cell produced con- 
tains only one nucleus, but several may be present, as in the zoogonidium of Vaucheria 
and in the oosphere of those Saprolegnieae in which there is only one oosphere in the 
oogonium. 
The 'whole of the protoplasm of the cell is not necessarily involved in this process, as 
is shown by the development of the antherozoid in many cases. 
Page 9. In the process of conjugation in Spirogyra the nuclei of the conjugating cells 
were observed by Schmitz (Sitzber. d. niederrhein. Ges. in Bonn, 1879) to coalesce. 
Page 10. From the researches of Schmitz on the Myxomycetes (Sitzber. d. nieder- 
rhein. Ges. in Bonn, 1879), it appears that the nuclei of the cells which coalesce to form 
the Plasmodium do not fuse but remain distinct : this case of coalescence of cells cannot, 
therefore, be any longer regarded as an instance of cell-formation by conjugation. 
Free cell-formation. From the account of this process given in the text, it is evident 
that the expression 'free cell-formation' is now used in a sense different from that which 
it originally possessed. In its original sense it implied the development de nonjo of 
fresh nuclei around which the protoplasm became aggregated so as to form cells: it is 
now applied to those cases in which many nuclear divisions take place before any cor- 
responding cell-divisions occur. Taken in this sense, free cell-formation differs only in 
degree from cell-division, and it is not possible to distinguish sharply between them : 
for example, the development of the pollen-grains of Dicotyledons is usually regarded as 
coming under the head of cell-division, but it may equally well be considered to be a case 
of very limited free-cell formation in which only four nuclei are produced by division 
before any cell-division takes place. 
It must not be assumed that there is no such thing as a formation of nucleiV<f no'vo. 
Strasburger (Bau u. Wachsth. d. Zellhäute) has pointed out that the appearance of the male 
pronucleus in the oosphere during fertilisation (see p. 584) is an instance of it, inasmuch as 
the nuclei of the pollen-grain do not pass directly into the oosphere, but break up and 
become diffused either in the pollen-grain or in the pollen-tube.. Johow has observed the 
breaking-up and the reconstitution of nuclei in Chara (Bot. Zeitg. 1881). 
Page 12. For minute details as to the development of spores and of pollen-grains, 
see Strasburger, Bau und Wachsthum der Zellhäute, 1882. 
Page 15. Cell-formation by Budding and Abstriction. Further instances of this are 
afforded in the formation of the spores of Pellia epiphylla and some other Liverworts. 
The mother-cell of the spores grows out into four protuberances, each of which becomes 
shut off by a septum in the narrow pedicle and forms a spore (Strasburger, Zelltheilung und 
Zellbildung, 1880). 
Page 16. Vegetati've Cell-formation. In the case of naked (primordial) cells division 
takes place by the gradual constriction of the protoplasm : this has been observed by 
Schmitz (Mittheil, aus der zool. Stat, zu Neapel, I, 1878) in the formation of zoogonidia of 
Halosphcera •viridis; by de Bary in the amoeboid zoogonidia of Myxomycetes; by Pring- 
sheim in the oospore of (Edogonium ; and by Kirchner in the oospore of Fohox minor. 
Page 17. The Beha-viour of the Nucleus during Division. The accounts of the structure 
of the nucleus and of its behaviour during division given by Flemming and by Strasburger 
do not agree in all points. The following are the principal differences between them : 
(i) Flemming holds that the chromatin only exists in the form of fibrillae ; (2) he does 
not agree with Strasburger that, in the splitting of the equatorial plate, any division of 
3 P 
