100 TYPE STUDIES 



96. Sargassum. Study the general morphology of Sargassum from dried 

 specimens on herbarium sheets. Note the stem, leaf-like lateral structures, 

 branching receptacles, stalked berry-like air bladders, and holdfast. Illustrate 

 these features. Is this structure a thallus ? 



THE EED ALG^, OE EHODOPHYCE^ 



97. Nemalion. Note the form and consistency of the thallus. 

 The color, which may be observed from herbarium material, is 

 not typical of the red algae. 



A. Crush out a tip under the cover glass. Under m.p. study 

 the vegetative structure composed of filaments held together 

 by a gelatinous substance. 



1. Diagram the form and arrangement of the filaments in 

 the interior and outer regions. 



2. Draw details of the vegetative cells under h.p., showing 

 the peculiar chromatophores and the attachment of the pro- 

 toplasts to one another by delicate strands of protoplasm. 



B. From a crushed-out tip of a male, or antheridial, plant study 

 the clusters of sperm mother cells forming <t,ntheridia at the 

 tips of the filaments. Draw. Each sperm mother cell devel- 

 ops a single non-motile sperm. 



C. From a crushed-out tip of a female, or cystocarpic, plant 

 study and draw : 



1. The large, mature, globular fructification called a cysto- 

 carp. The development of its spores, carpospores, at the 

 tips of filaments. 



2. Earlier conditions. Search for the female organ from 

 which the cystocarp is developed. The female organ is a 

 single cell, carpogonium, corresponding to an oogonium. It 

 is situated at the end of a short branch, and bears a delicate 

 extension, the tricJiogyne, an organ for the reception of the 

 non-motile sperms. Draw a carpogonium with trichogyne, 

 probably having one or more sperms attached, or some early 

 stage in the development of the cystocarp when the fer- 

 tilized carpogonium may be divided into several cells. 



