136 Johnson. — Observations on Phaeozoosporeae. 
in the main, right in his conjecture. In C. Cabrerae , the 
branches of which are sub-cylindrical, the hairs at the 
growing-point (Fig. 2) radiate outwards and, frequently, 
branch. A thallus-branch with its apical tuft of hairs is 
roughly comparable to a paint-brush. The hairs are con- 
nected through the punctum vegetationis with the cells of the 
thallus, but not so directly in series as in Cutleria multifida. 
Each hair exhibits basal growth ; cells are given off, on the 
distal side to the base of the hair, the terminal cells of which 
fall off, on the proximal side to the body of the thallus. The 
hairs are free from one another to the merismatic region, 
but the cells given off on the proximal side are cemented 
together, and build up the compact thallus. They undergo 
intercalary divisions and form the parenchymatous thallus, in 
the branches of which a midrib is, at a little distance from the 
apex, well marked. It is of interest to note that the hairs, 
having chlorophyll in their joint-cells, are capable of con- 
siderable assimilative activity, as a result of which the meris- 
matic region, from which new cells are being steadily derived, 
is well supplied with food h It is not difficult to see how, by 
a grouping together of simple, uniseriate, uncorticate, tricho- 
thallic branches, the mode of growth in C. Cabrerae can be 
derived from the well-known mode in Ectocarpus . 
Reproductive organs. The sessile terminal mitre-like 
receptacle (as the fertile tip is called) gives to Carpomitra 
its name (Fig. 3). The sporangia form, with the paraphyses, 
a dense covering at the tip of a branch. The paraphyses 
are simple or, more generally, branched, and, when branched, 
often dichotomous. The sporangia are sessile or stalked, 
the stalk being provided by the paraphysis (Fig. 4). The 
terminal cell of the paraphysis contains chloroplastids, and 
not, as thought by Harvey 1 2 , £ probably the remains of sper- 
matozoa.’ Each sporangium is unilocular and contains a 
1 The assimilative powers of the tufts of hairs in the Australian genera Bellotia 
and Encyothalia must be very great. In these genera the mode of growth is no 
doubt the same as in C. Cabrerae. 
2 W. H. Harvey, Phyc. Brit. PI. 14. 
