THE MARINE ALG.E OF NEW ENGLAND. 15 



and spring than at other seasons, if we except a few genera, like Ecto- 

 earpus. The conjugation in this suborder was first seen by Areschoug 

 in Dictyosiphon, and afterwards by Goebel in Ectocarpus pusillus. The 

 zoospores unite in nearly the same way as in the Chlorosporew. Accord- 

 ing to Goebel, who studied the zoospores coming from plunlocular 

 sporangia, the conjugation occurs between zoospores coming from dif- 

 ferent sporangia. The development *of the zygospore and the action of 

 the zoospores borne in the unilocular sporangia, except in the genus 

 Dictyosiphon, are not yet satisfactorily known. Thuret and Bornet have 

 seen bodies which they consider to be antheridia in several species of 

 Ectocarpus, and Pringsheim at one time considered that he had found 

 antheridia in a species of Sphacelaria. It is now admitted that the bodies 

 found by Pringsheim belonged to a parasitic species of Chytridium, and 

 Thuret and Bornet were unable to ascertain the development of the 

 antheridia in Ectocarpus. At any rate, nothing like an oogonium or any 

 female organ to be fertilized by the antherozoids has been found in the 

 Phwosporem. 



As has already been hinted, the genera of Phceosporem differ from 

 one another very widely in the structure of the frond. From low 

 forms, consisting of short filaments, we pass upwards, through various 

 cylindrical, crustaceous, and globose forms, to the highly developed 

 devd's aprons, Laminarece, the largest of our sea- weeds; and, finally, 

 on the coast of California and in the Antarctic Ocean, we find the per- 

 fection of the order in the enormous Macrocystis pyrifera, which is sev- 

 eral hundred feet long ; the Nereocystis or bladder-kelp of California ; and 

 Egregia, in which we have what appears to be a separate stem, leaves, 

 bladders, and fruit-bearing leaves. Janczewski distinguishes three prin- 

 cipal modes of growth of the thallus in Phmosporece. The first consist 

 in growth from a single terminal cell, as in Sphacelaria, Oladostephus, 

 and Dictyosiphon, resulting in the formation of a filamentous solid plant. 

 The second mode consists in the simultaneous growth of several contigu- 

 ous filaments at their tips, so as to form either a flat expansion, as in 

 Myrionema and Balfsia, or a more or less globular body, as in Leathesia. 

 The third mode is illustrated by the genus Lamlnaria, in which there is 

 a stalk, a blade, and root-like growths. The place of growth is at the 

 point of union of stem and blade, and the new blade, which begins to 

 form at the tip of the stem, grows upwards from the base and gradually 

 pushes off the old blade. In Scytosiphon a similar mode of growth is 

 found only here, there being no stalk,, the growth is at the base of the 

 plant. During a certain part of the year, especially in the spring, most 

 of the Phceosporeo3 are covered with delicate hairs, which disappear as 

 the plant becomes old. 



The suborder contains a large number of species, which are divided 

 into several families. Those found on our coast are the following : 



ScYTOSiPHONEiE. — This family includes the two genera Scytosiphon 

 and Phyllitis, which comprise the old Chorda lomentaria and Laminaria 



