Dr. Willshire^s Contributions to Structural Botany. 83 



cells, so is the breadth of the frond. The same process of di- 

 vision takes place with each series of primary cellules, so that 

 supposing four series to have been developed, there will be 

 seen eight rows of tertiary cells. In those plants assuming 

 the flattened and laterally extended form, the markings of the 

 different series are very and beautifully evident, they being 

 divided from each other by bright longitudinal bands, and 

 which are much more evident than the transparent lines se- 

 parating the tertiary cells from each other ; in fact, the latter 

 are almost disregarded by attention being attracted so strongly 

 to the former, which I would therefore denominate the serial 

 bands, the others the cellular lines. Very often the cellular 

 lines are completely obliterated as transparent ones by the 

 pressure of the granules in the opposed cells, a dai^k line re- 

 sulting from the close approximation of the edges of the gra- 

 nules. It is the serial bands to which specific distinction 

 has been attached. When the series of primary cellules in- 

 crease suddenly in number, a transverse cellular band is seen 

 running across the frond where its increase of breadth com- 

 mences ; and even in fronds preserving the same serial condi- 

 tions throughout their length, these transverse bands are to be 

 seen at places where there is evident constriction. The ter- 

 tiary division of the cells being complete, the green granular 

 matter contained in each of the four cells resulting from this 

 division becomes separated into four portions, each portion or 

 mass apparently being enveloped by a cellular covering, thus 

 resembling somewhat four agglomerated granules of pollen. 

 As far as I have been able to discern, the quatenary division 

 of the granular matter does not result from a further division 

 of the tertiary cell, but from a plastic power exclusively its 

 own. When the granules are observed moving about after 

 their separation from the frond, they are sometimes noticed 

 adhering in fours, as they do in the cells ; at other times they 

 separate very soon from each other, each little one moving 

 about by itself, and marked with a dark central spot. The 

 general colour of the granules is certainly that of a bright 

 green ; but others, and which are the largest, and generally 

 those w^hich have only undergone a binary division, are of a 

 much deeper and more olive-green hue. It is very evident 

 that the plant is quite destitute of colour, independent of that 

 which it receives from the granular or sporidial matter ; to me, 

 also, that the youngest condition of the plant is cylindrical and 

 cellular, in fact confervoid ; and also that this condition may 

 remain, and yet the plant perfect quaternary granules. In 

 the metamorphosis of it to the flattened form, the interserial 

 spaces and margins become thick and much developed, pre- 

 senting quite a homogeneous appearance, the frond often 



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