M. Miiller on the Development of Chara. 255 
organs can be no longer obtained, the substance being destroyed 
by winter, and as at the next opportunity I may not. have the 
leisure for continuing these researches, I shall present here the 
observations which I have collected. 
As regards the history of this family, we find in Kaulfuss’s 
paper* a complete sketch of it up to that time, to which I must 
refer ; subsequently, Bischoff +, Schultz { and Meyen$ have made 
valuable contributions. Kiitzing || has detailed some general 
observations, and Fritzsche some beautiful investigations on the 
anthers in his paper, “ Ueber den Pollen” {, which however leave 
several points open for future observations. Nageli has lately 
written on the moving spiral fibres in the mucous threads of the 
anthers**, and Mettenius on the same subject in the ‘ Bot. Zeit- 
ung,’ 1845. 
Considering the labours of these observers as known, I shall 
confine myself strictly to my own investigations. But as we have 
to commence the history of the development with the germ, I 
do not consider it superfluous again to give a description of the 
spore in that stage in which it has attained its greatest deve- 
lopment (especially as it contains some new facts), because by a 
knowledge of the organ, in which the formation of the new plant 
occurs, our knowledge of the process itself must become more 
perfect. 
§ 2. The Ripe Fruit. 
When divided through the axis it appears composed of three 
distinct coverings: 1. an external one (the spore-sac) ; 2. a mid- 
dle one (the sporular membrane) ; and 3. an internal one (the 
nucleus) (Plate V. fig. 1). 
€ spore-sac is a thick, more or less pyriform covering, upon 
the apex of which five approximated thick cells are situated, 
forming a kind of crown. This covering is formed of five cells, 
-which are spirally wound around the spores several times—usually 
twice. The former five short cells form the summit of the spores. 
Each of these cells when divided appears four-sided, their inner 
surfaces being flattened towards the spores, the outer ones to- 
wards the atmosphere, and the lateral ones towards each other. 
The planes of the latter however are arranged in an undulatory 
manner. These, like the former cells, are composed of three 
distinct membranes; an external one or epidermoidal mem- 
* Erfahrungen iiber das Keimen der Charen, Leipzig, 1825. 
+ Krypt. Gew. 1 Lief. 1828. 
+ Natur d. Jebendigen Pflanze, Bd. 2. p. 470. 
§ Physiologie, especially in the third volume. | Phycolog. general. 
4] Mém. de l’Acad. Imp. des Sc. de St. Petersbourg. 
** Ztschr. f. phys. Bot, Bd, 1. Heft 1. p. 168. 
