REJUVENESCENCE IN NATURE. 253 



tinct cell, while no new nucleus is formed in the longer, 

 posterior part of the cell. According to Hofmeister,* 

 the second cell of the proembryo (the cellular filament 

 first developed from the germinal vesicle, the suspensor) 

 is formed in a manner essentially the same, in Monotropa,-^ 

 Gagea,% Fritillaria, Martynia, and Linwm. 



b. A lateral growth from the cell {a cell-branch) 

 becomes shut-off as a separate cell. This process also 

 may be repeated in the same mother-cell when several 

 branches arise from it one after another, as occurs in 

 Cladophora glomerata. The branches arise sometimes 

 from the upper margin, sometimes from the lower, and 

 sometimes from the middle of the cell ; sometimes from 

 the upper and lower border at the same time, as men- 

 tioned already of Chmtophora and Coleochate pulvinata 

 (p. 150). According as the ramification commences in 

 the earliest youth of the cell, or at a later epoch, in 

 somewhat advanced development of the cells, the shutting- 

 off of the branch may exhibit distinctions of mode and 

 kind, analogous to those we have characterised as young 

 cell-division and old cell-division. 



a. Without a nucleus ? Ramification of Cladophora, 

 Chantransia, Chroolepus, Draparnaldia, Chcetophora, &c. 

 In many of these genera the nuclei have certainly been 

 merely overlooked. 



j3. With a nucleus. Here belong the Fucoidese and 

 Floridese, in the ramification of which, according to 

 Nageli's conjecture, § the original nucleus remains in the 

 cavity of the mother-cell, while a new nucleus is formed 

 in the protrusion becoming the branch-cell. 



With these " baggings-out" of the cells, giving origin 

 to the branches of the lower plants, may be compared, 

 to a certain extent, the thylls, those remarkable cell-like 

 structures which fill up the wide vessels of wood in old 



* Hofmeister, 1. c, p. 6. 

 t Ibid., p. 36, t. xii, f. 9—14. 

 \ Ibid., p 22, t. ix, f. 9—14. 



\ ' Zeitsohr.,' 1847, pp. 71, 72, (Modes of Cell-formation, 8 a and b.) 

 (Eay Transl., 1849, pp. 141, 142.) 



