West & West, — Observations on the Conjugatae, 37 
We have often noticed these cells begin to divide actively 
and ultimately produce new filaments (Figs. 62 and 65). That 
their activity is increased is also proved by the extraordinary 
development from these cells of swellings and processes, which 
so often occurs as an accompaniment to conjugation (cf. 
Fig. 58). Moreover, as previously mentioned, some cells by 
reason of this activity are induced to put out conjugating- 
tubes, which, not meeting with others, and not being able to 
fulfil their proper function, ultimately become rhizoids or 
organs of attachment. 
FAM. I . — ZYGNEM ACEAE. 
Sub-fam. 1. — Mesocarpeae. 
This sub-family includes two genera, Gonatonema , com- 
prising but four species, and Mougeotia , comprising upwards 
of thirty species. 
1. Mougeotia. This genus now includes, and we think quite 
correctly, the genera Mesocarpus, Craterospermum, Plagio- 
spermum and Staurospermum , all those characters regarded 
in the past as generic distinctions having been found by 
Wittrock 1 to be present in one species (M. calcarea). Many 
other observations also tend to prove the identity of these 
so-called genera. The conformation of the young zygospores 
of M. uberosperma (not taking into consideration the four 
outer processes) is decidedly that of a Staurospermum , whereas 
the adult zygospores are almost globose (cf. Figs. 42 and 43). 
In this genus an axile plate-like chromatophore is present 
in each cell ; and so far as our observations go, there is but 
one exception to this, M. capucina having an axile sub- 
irregular rod of chlorophyll connected to the lining primordial 
utricle by fine colourless threads of protoplasm. The rest of 
the cell-cavity between these meshes of protoplasm is filled 
with purple-coloured cell-sap 2 ; the nucleus also stands out 
1 V. B. Wittrock, Om Gott. och 01 . Sotv. Alg., Bih. till K. Sv. Vet.-Akad. 
Handl., Bd. i, No. i, Stockholm, 1872. 
2 Cf. remarks on this species by Lagerheim, Ueber das Phy coporphyrin, 
Vidensk.-Selsk. Skrift., I. Mathem.-natur. Kl., Kristiania, 1895, No. 5, p. 6 (Sep.). 
