I 



Linnaan Society. 499 



tubes attenuated towards each extremity, and filled at first with an 

 almost colourless coagulable protoplasm. After a short time starch 

 globules are seen within them, which might readily be mistaken for 

 the rudiments of the spiral fibre ; but the author believes that the 

 accounts given by some writers of the formation of spiral fibre in 

 spiral vessels from rows of minute granules are incorrect, and have 

 arisen from observation of starch granules lying in rows often 

 running obliquely across the tubes. After a greater enlargement 

 in the length than in the diameter of these cells the starch granules 

 and finally the protoplasm disappear, and faint streaks denoting the 

 nascent fibres are at length visible upon the walls. These gradually 

 become more and more distinct, until in the mature elaters they pre- 

 sent themselves in the form of strong flattened bands. In Marchantia 

 there are two fibres, the ends of which are confluent at the extremities 

 of the tubes in which they are contained ; so that more properly 

 speaking there is but one endless fibre twisted upon itself, which 

 may be represented by a piece of string doubled with its ends 

 united, and twisted spirally upon itself. This is evidently the best 

 possible condition of structure for its purpose of acting as a spring. 

 In unrolling, the fibre tears up the membrane of the walls of the 

 tube, which after the elaters have been discharged is often no longer 

 to be detected. 



While the elaters are passing through these stages the larger 

 elongated cells exhibit a very remarkable series of changes, which 

 Mr. Henfrey regards as diflfering from anything that has yet been 

 observed in analogous structures. They are at first filled, like the 

 elaters, with a delicate colourless protoplasm, in which float ex- 

 ceedingly minute granules, and which is apparently the same sub- 

 stance that occurs in all young cells which increase by self-division. 

 These larger cells soon exhibit transverse streaks of a lighter colour, 

 in consequence of the separation of the protoplasm into a number 

 of distinct portions, and the formation of cross membranes at these 

 places, dividing the tubular cell into a row of cells, all of a square 

 form except the two terminal ones which are attenuated towards the 

 free point. The author could not determine whether the septa were 

 formed by gradual growing in of the membrane, nor could he detect 

 at this period a double membrane, which must, however, exist, to 

 admit of the subsequent separation of the contained cells. Vertical 

 septa are often formed in addition, producing a double row of cells 

 within the tube. About the time when the cells separate from each 

 other, their contents undergo a change, which exactly resembles 

 that which occurs in the contents of the parent-cells and special- 

 parent-cells of pollen when the formation of free cells is about to 

 take place in their interior. The mucilaginous matter, or protoplasm, 

 acquires a deep yellow colour, becomes much thicker, and exhibits a 

 quantity of globular bodies which look like drops of oil. Mr. Hen- 

 frey/ gives his reasons for regarding these appearances neither as 

 drops of oil nor as vesicular cavities, but as globular drops of the 

 yellow protoplasm. Such globules are of various sizes and some- 

 times occupy half the cavity of the cell, but neither before nor after 



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