Tilden: MORPHOLOGY OF hepatic elateks. 47 



describing sections cut from young sporogonia of FruUania 

 dilatata he states^^: "The cells with dense protoplasm are al- 

 ready divided into two categories; some elongate simply with- 

 out dividing, the others elongate in the same manner, but 

 divide. The first form the elaters, while the others give birth 

 to spore mother-cells." And farther on: " It is interesting to 

 remark in the case of FruUania that each elater is equivalent not 

 only to a spore mother-cell but to a row of them." He gives the 

 following account of the development of the elater cells of 

 FruUania dilatata^*: "At first the elaters have a thin mem- 

 brane of cellulose. But from this moment the evolution of the 

 membrane from two sorts of elements is essentially different. 

 While the protoplasm of the spores condenses and becomes re- 

 serve material, the contents of the elaters are seen to diminish, 

 employed partially at least in the formation of the spiral, 

 which, as is said, is an internal ornament of the membrane. 

 This role of nourishing the spore mother cells is generally 

 attributed to the protoplasm of the elaters. The formation of 

 this spiral appears to be comparable to that which has 

 been described by Strasburger in spiral vessels. One" 

 observes at a certain moment, while the elater is still com- 

 pletely filled with protoplasm, that it forms upon the mem- 

 brane a thin, colorless, granular line, which is the first index 

 of the formation of the spiral. Little by little this band thick- 

 ens, its outline becomes distinct, and one sees the spiral appear, 

 still delicate and colorless, but with the form which it must 

 preserve. During this time the interior protoplasm diminishes 

 in volume, it falls away, so to speak, while the spiral thickens. 

 Afterwards the protoplasm completely disappears; the spiral 

 is formed and the elater arrived at its definite state, finds itself 

 reduced to the state of a cellular skeleton of which the role 

 henceforth is known to be only of a purely mechanical order.' 

 As quoted by Bennett and Murray,^ Leclerc du Sablon found 

 the sporogonium of the typical Hepaticae to be composed at an 

 early stage of sixty- four cells, each of which subsequently 

 divides into four. These cells elongate in the direction of the 

 axis of the sporogonium and then become differentiated into 

 two kinds. "In the one kind the nucleus undergoes repeated 

 bipartitions, and these give rise to the spore mother-cells; in 

 the other kind the nucleus does not divide, and the protoplasm 



33. Leclerc clu Sablou, loc. cit. 134. 



34. Leclerc du Sablon, loc. cit. IHH. 



35. Bennett and Murray, llaudb. of Crypt. Bot. 150. 1889. 



