572 Transactions of the Society. 



Farlow and Bornct mention a few species in which individuals have 

 been met having both kinds on the same individual, and we once 

 found a single plant of Polysiphonia byssoides bearing well- 

 developed tetraspores and cystocarps. Some algologists in de- 

 scribing the species included under Palmellaceoj and other primitive 

 families, use the term " multiplication " to denote what we have 

 termed vegetative reproduction, and " propagation " when reproduc- 

 tion is effected by specialized portions, sexual or otherwise, hence 

 we presume the terms would be equally applicable to define the two 

 methods of reproduction met with in the Floridese. 



In a carpological arrangement Floridese stand at the head of 

 the algal family although the vegetative parts, as a rule, are less 

 developed than in the brown seaweeds belonging to Fucaceas and 

 Laminar iete. 



The following are the most marked types of thallus develop- 

 ment met with in Floridese. 



1. When the substance and outline depend entirely on the 

 development of branches of definite growth, springing in a whorled 

 or scattered manner from axial cells ; these branches are of equal 

 length and densely corymbose at the tips, which are cemented 

 together, forming a false parenchymatous tissue towards the 

 surface of the thallus, the interior remaining spongy. If the 

 branches all develope equally a cylindrical thallus results, but if 

 growth is unequal and most pronounced in one plane, a flat thallus 

 is produced. The flattened thallus is always evolved from a 

 cylindrical type, in other words the mode of branch arrangement 

 observable in a flat thallus can always be met with in a less 

 differentiated manner in the cylindrical stage, and connecting the 

 two there is every transition. 



The following genera illustrate the sequence of development of 

 this type : — 



Batrachospermum, branches in whorls, equally developed, 

 whorls distant. 



Crouania (schousboei Thur.), branches in approximate whorls, 

 but not agglutinated together. 



Calosiphonia (finisterrse Crouan), whorls equally developed 

 and approximate, the external cells agglutinated together and form- 

 ing a continuous cylindrical thallus. In the above example the 

 branches spring from a single row of axial cells ; in 



Solieria (chordalis J. Ag.) the thallus is cylindrical as in 

 Calosiphonia, but instead of a single axial row of cells there are 

 several rows, from which the branches spring. 



Polycoelia shows the transition from a cylindrical to a flattened 

 thallus. The branches originate from a single axial row of cells ; 

 but the lateral branches grow much longer than the anterio-pos- 

 terior ones, producing a thallus with a more or less compressed 



