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BOTRYDIUM GRANULATUM, (DESV.) 

 By E. Parfitt. 



This curious little plant, which is not uncommon in certain 

 places in the neighbourhood of Exeter, and it is also generally 

 distributed both in England and Scotland, has been known to 

 botanists for a very long time, but as Dr. Greville observed in his 

 Algae Britannic* in 1830, and I believe up to the present time, its 

 fructification is not known, and so far as I have been able to find, 

 the true structure, and peculiar physiology, have not been studied. 

 Dilwyn in his" British Conferva?" p. 79 has done more to illustrate 

 some of its peculiarities than any of the numerous writers that I 

 have consulted, if his be really the same species that I have in 

 view, and it differs only in one particular, and that is, he has made 

 the underground stems in his figures septate. He says, " the joints 

 are very long in the creeping stems," which is perfectly true. I have 

 observed but one septum in the many specimens that I have ex- 

 amined. Dr. Greville has very accurately described this little 

 plant, so far as a general description goes, and which is rendered 

 quite sufficient for its distinction, but he has gone no farther. The 

 Doctor says, " Plant about the size of a pin's head, sessile upon 

 the surface of the ground, covering a large space in a densely 

 crowded manner, composed of a hollow vesicle, not homogeneous 

 as in the genus Vancheria, but filled with a watery fluid, which 

 escapes by an irregular terminal orifice. The receptacles at length 

 collapse, become cup-shaped, and then cover the ground with a 

 thin greenish crust, like that of some lichens. At its under part, 

 each receptacle is terminated by a very short neck, which divides 

 into a radiating tuft of pale fibres. Substance fragile and mem- 

 branaceous, colour a pale green," and he adds to this — " The 

 fructification of this plant is not known! Does the watery fluid 

 contain it ? The structure of the receptacle seems minutely 

 granular." In this description it will be observed nothing is said 

 about the underground stems being septate. We may from this 

 infer that Dr. Greville did not observe them. The specific name 

 of this plant is granulatum, and as Dr. Greville and others have 

 said, its surface seems minutely granular. Now this I have ascer- 

 tained by careful microscopic examination to be not external, 

 although the effect is seen on the surface of the vesicles, but it 

 results from the pressure of the protoplasm and grains of 

 chlorophyll on the inside. 



The membranes composing the walls of the vesicles, for there are 

 two, an outer and an inner membrane, although this cannot be 

 ascertained w T ith certainty, except at the base of the vesicles and 

 where the inner membrane begins to dry up when it shows in folds, 

 by carrying, and the breaking up of the endochrome, into folds 

 with it, and in the underground stems, where they are distinctly 

 visible, they appear to me to be perfectly structureless, that is, they 



