146 W. H. HARRIS ON MARINE MICROSCOPIC VEGETABLE ORGANISMS. 



become separated into little detached masses, and if the specimen 

 is one of the filamentous description these detached masses can 

 be seen to be still further breaking up until small globular or 

 subglobular bodies are found, which are probably reproductive 

 elements of the nature of spores ; these ultimately escape through 

 the perforations, the majority of specimens being devoid of these 

 bodies. The little flask-shaped cavities are also occasionally 

 packed with similar bodies, either colourless or of a rich amber 

 tint. 



The multiplication of individuals of the last-named division can 

 be very easily studied if uncrowded fragments are selected for the 

 purpose. The process appears to be as follows : the reproductive 

 body having found a lodgment upon a piece of shell, burrows into 

 its substance ; after the perfect flask-like form is assumed, very 

 fine filaments are produced from the bottom or sides of the 

 globular portion of the organism, sometimes extending for a con- 

 siderable and at other times for a comparatively short distance. 

 I am disposed to think this feature has a specific value, which 

 further investigation may possibly reveal. Whatever distance 

 they traverse the shell, their tendency is to reach its surface ; and 

 as soon as this occurs the growth again plunges into the shell, a 

 duplicate flask is formed, and the process is repeated until the 

 fragment is riddled with the cavities thus formed. One feature 

 which appears to be constant is that the secondary cavities always 

 occur at a point very slightly removed from the distal end of the 

 filament. 



Frequently both sides of a fragment of shell contain specimens 

 of the same species of the filamentous kinds ; among the robust 

 varieties these are probably produced by the growth of the 

 organism around the edges of the fragment, or they may plunge 

 through its substance and reappear on the opposite side. I do 

 not remember having met with a single example of multiplication 

 of individuals taking place on the same system as observed among 

 the Lacunae ; I am therefore disposed to think they originate 

 from a spore-like organism and not by a vegetative process. 



The margins of the fragments of shells are frequently crowded 

 with forms in their early stages of growth, the position apparently 

 ofiering suitable lodgment for and protection to the repi-oductive 

 bodies'-until- growth - has - commenced. In many instances the 

 fracture has been caused by the erosion of the shell by the plant ; 



