OLIVE COLORED ALG^. 113 



composed of cells put end to end in a single series. 

 The determination of species is made, in most cases, 

 by the appearance of the fruit masses, (propagula ) . 

 and by the peculiarities of the branching. These 

 points can best be determined by the use of the 

 compound microscope, but they can be made out 

 with a good pocket lens. They are mostly parasitical 

 on other Algae, Fucus, Chorda, Chordaria and 

 Zostera, etc. The color of the smaller fonns is very 

 apt to be a fine olive green. 



Ectocarpus FIRMUS, Ac {E. littoralis, Harv.) 



This is said to be the commonest species of the 

 genus on our coast, and grows parasitical on the 

 littoral Fuci. The tufts are of various lengths up to 

 ten or twelve inches, dense, filaments fine, interwoven, 

 much and irregularly branched ; branches mostly 

 alternate, repeatedly divided, the divisions made at 

 acute angles, the upper unes opposite; articulations 

 of branches almost as long as broad. The propagula 

 form elongated linear swellings in the substance of 

 the greater and lesser branches, many times longer 

 than broad. Color varies from olive green to brown. 

 Found at all ^ea^ons. 



