56 



MU SCALES. 



[ACROGENS. 



A remarkable point of structure in Liverworts is the spiral filament, or elater, as it is 

 called, lying among the spondee within the spore-case. This consists of a single fibre, 

 or of two, twisted spirally in different directions, so as to cross each other, and contained 

 within B very delicate, transparent, perishable tube. They have a strong elastic force, 

 and have been supposed to be destined to aid in the dispersion of the sporules, — a most 

 inadequate end for so curious and unusual an apparatus. It is more probable that they 

 are destined to fulfil, in the economy of these plants, some function of which we have 

 do knowledge. 



( iin- of tin most extraordinary points in the history of the Muscal Alliance, is the fact 

 that in the cells of tho antheridia are generated bodies having what seems to be 

 spontaneous motion, and apparently of the same nature as the spermatic animalcules of 

 animals. This unexpected fact has been fully and correctly described by Meyen, 

 < Ann. 8e> Nat. N. S. x. 319), who has found the same creatures (?) in the correspond- 

 ing organs of Chara and Mar- 

 chantia. Unger has also pub- 

 lished an elaborate Memoir 

 upon this singular subject. 

 (A nn. Sc. N. S. xi. 257 and 274.) 

 He describes the spiral threads 

 of Sphagnum thus : — " These 

 animalcules consist of a thick 

 and swollen body having a 

 slender threadlike appendage. 

 The length varies between the 

 Fig. XXXV. 0.0025 and 0.0020 or ^ to 



xfo of a line Vienna measure. The length of the appendage is about 4 J longer than the 

 Cody, so that the total length of the animal may be stated to be the 0.01 of a line." 

 1 1 is to be observed by those who may search for such bodies that they can oidy be 

 found just when the antheridium is completely formed, and that a magnifying power of 

 at least 600 diameters is required for their detection. Unger regards them as analogous 

 to the genus of animalcules called Spirillum. It is so improbable that animals should be 

 generated in the cells of plants, unless accidentally, that we cannot but entertain grave 

 doubts whether, notwithstanding then' locomotive powers, these bodies are really any 

 thing more than a form of vegetable matter ; and it is worth considering if they may 

 not after all be a diminutive representation of the clavate processes surrounding the 

 spore "f Equisetum, and perhaps of the elaters found in the spore-cases of Liverworts. 

 This is certain, that the spores and elaters of Equisetum, when at rest, have very much 

 the appearance of the Spirilla in the antheridium of an Urn Moss or a Chara ; and since 

 it has been proved that the spiral filaments of Equisetum arise from the splitting of a 

 cell in which a spore is generated, there seems no reason why a similar action should 

 not take place in cells that arc destitute of spores. As to the motion, how are we to tell 

 that it is not a hygrometrical action ? There is as active a motion in the elaters of 

 Equisetum as in the spirilla of Mosses, only it arises in the former from drying and in 

 the latter from Boating in water. Niigeli has lately found the spiral threads of Liverworts 



in the leaves of ferns. 



Equisetum may be regarded as a link between this alliance and Chara on the one 

 hand, while its high degree of composition brings it into the neighbourhood of Ferns 

 and Clubmosses. 



By Borne Botanists the orders of the Muscal Alliance are separated into two great 

 groups, Hepaticee and Musci ; of which the former are without an operculum and have 

 lor the most part elaters, while the latter have an operculum and always want elaters. 

 Bui such distinctions seem to he of hardly sufficient importance to be employed for 

 higher purposes than the distinction of Natural orders. 



Natural Orders of Muscals. 



1. 1 1 KIWI! 



Spore-cases valveless, vrithout operculum or elaters . . 15. Ricciaceje. 

 Spore-cases valveless or burstiw/ irregularly, without, \ ,„ „„ 



vperculwn, but with elaters . .'. .'. . . . J-16. Mabchantiacb*. 

 Spon -cozes opt ni/ng by a definite number of equal valves, 1 , _ T 



without op\ rcutim, but with , hit «... . \ ) 17 - Jungermanmacm. 



Spore-cases peltate, splitting on one side, without oper-\ 

 cukm, and wit h an elater to every spore ... .J 

 Musci. 



Sport -cases opening by valves, with an operculum, with-\ 



18. Equisetace.e. 



OUt , la* r,' '""". "*. "."".' 7""." T "f"™"' ™ J 19. ANDRyEACE*. 



>/ on -cotes valveless, with am opt rculum, without elaters . 20. Bryacea. 





