THE MARINE ALG.E OF NEW ENGLAND. 19 



female by the brighter color of the tips which bear the conceptacles. 

 A section through the conceptacles of the male plant, as in PI. IX, Fig. 2, 

 shows a number of branching filaments which line the interior of the 

 conceptacle. Attached to the filaments are oval bodies, the antheridia. 

 The antheridia contain the antherozoids, which are ovate and provided 

 with two cilia attached at the side. Usually about day-break the an- 

 theridia discharge their antherozoids, which then swim about in the water 

 until they reach the female plant. A section through the tip of a 

 female plant shows a number of conceptacles similar in shape to those 

 of the male plant. On the walls of the conceptacle there are paraphyses, 

 and scattered among them are the oogonia, as shown in PI. IX, Fig. 1. 

 The oogonia are oval and seated on broad short pedicels. In Fucus 

 vesiculoms the contents of the oogonia divide into eight oospheres, which 

 are at first angular, but afterwards become spherical. The oogouia be- 

 come free from their attachments, and the wall, which is really double, 

 ruptures, and the oospheres escape into the water. In this condition 

 they are merely spheres of protoplasm. The antheridia then collect 

 around the oospheres in large numbers, and the mass begins to ro-< 

 tate. The rotation continues for a short time, and when it ceases the 

 antherozoids withdraw and soon perish. It is not yet certain whether 

 one or more of the antherozoids really penetrates into the substance of 

 the oosphere during the revolutions. As soon as it comes to rest the 

 oosphere takes on a cell- wall of cellulose and becomes an oospore, which 

 after an interval of rest begins to divide so as to form eventually a new 

 frond. 



Dictyote^e. — Although no members of this order are known on our 

 coast north of Xorth Carolina, the order cannot pass unnoticed in the 

 present article, because it forms a connecting link between the Fucacece 

 and Phceosporetc on one hand and the Floridecv on the other. The 

 species are olive-brown and form expanded membranous fronds. Three 

 kinds of reproductive organs are known, antheridia, spores, and tetra- 

 spores. All are formed by outgrowths from the superficial cells. The 

 tetraspores are formed, as the name implies, iu fours in a mother cell, from 

 which they escape and then readily germinate. The spores are borne 

 singly in a mother cell. The antheridia are composed of a number of 

 oblong cells, which become divided by numerous longitudinal and trans- 

 verse divisions into small cells, each of which contains an antherozoid. 

 The Dictyotacem resemble the Floridew iu having tetraspores and 

 spores which germinate without first passing through a zoosporic con- 

 dition. The action of the antherozoids is at present unknown, and the 

 spores of this order cannot be the product of a fertilization such as we 

 find in the Floridece. 



Floride^e. — This order is the same as the Rhodospermece of Harvey's 

 Xereis. The species composing it form a very natural group, and are, 

 with the exception of a few genera, entirely marine. Their color is al- 

 ways some shade of red or purple when they are growing in their nor- 



