20 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



mal condition. When, however, they grow in positions where they are 

 much exposed to the light they become green, and in decaying they pass 

 through various shades of orange and yellow to green. Their favorite 

 place of growth is below low- water mark and in deeper water, but some 

 species grow in tide-pools. The fronds vary in structure in the different 

 genera, but as a rule they are less complicated than the fronds of the 

 Fuel and Laminar iece. The non-sexual mode of growth is by means of 

 bodies called tetraspores, formed by the division of a single cell into four 

 parts. The divisions may be at right angles to one another, when the 

 tetraspore is said to be cruciate; they may be parallel to each other, in 

 which case the tetraspore is said to be zonate; or they may be arranged 

 as in PI. XI, Fig. 1 a, when it is said to be tripartite. The tetraspores may 

 either be isolated or collected in wart-like masses, called nemathecia. 

 The individuals which bear the tetraspores are, with rare exceptions, dis- 

 tinct from those which bear the sexual fruit or cystocarps. Occasionally 

 both kinds are found on the same individual, as sometimes happens in 

 Callithamnion Baileyi and Spyridia Jilamentosa. The tetrasporic plants, 

 taking the order as a whole, are decidedly more abundant than those 

 which bear the cystocarps. The sexual fruit, called the cystocarp, is 

 formed by the action of antherozoids upon a structure called the 

 trichogyne, which forms a part of the procarpe. The antherozoids are 

 small colorless spheres, destitute of cilia. They are borne siugly in 

 cells, which are agglomerated in various forms, which differ in the dif- 

 ferent genera, but are usually either in the shape of short, dense tufts, 

 or else are siliculose in outline. In Chondria the antheridia cover the 

 surface of irregular disk-like branches, and in membranous genera 

 they form spots on the surface. 



The name of procarpe was given by Bornet and Thuret to the collec- 

 tion of different cells, of which the female organ is composed before 

 fertilization. The procarpes are borne on the younger parts of the frond 

 generally near the surface. The cells of which they are composed may be 

 divided into two sets — those which take part in the act of fertilization 

 and those from which the spores are formed. The former consists of 

 the trichogyne, a long, slender, hyaline hair, at whose base is the 

 trichophore. The latter set, called by Thuret and Bornet the carpogenic 

 cell or system, varies in the different genera, and is in most cases too 

 complicated to be explained in the present article. In the simplest geu- 

 era, as in Nemalion and Batrachospermum, the antherozoids come in con- 

 tact with the extremity of the trichogyne, where they remain fixed for 

 a considerable time. The contents of the antherozoid, or antherozoids — 

 for more than one may be attached to the trichogyne — pass into the 

 trichogyne, and, in consequence of this action, a change takes place in 

 the trichophore, which divides, the divisions growing into short fila- 

 ments, which are formed into chains of spores by transverse divisions. 

 In this case the trichophore represents the carpogenic cell. In Nemalion 

 the cystocarpic fruit is a globular mass of spores, arranged in filaments 



