78 HARTIG, ON DILUTE SULPHURIC ACID ON 



represented the mother-cells, whilst the divisions of this mass 

 have been secondary, tertiary, &c., cells. Lastly, the sperma- 

 tozoids themselves have simply been the last generation of 

 cells, separating themselves almost in the manner of vegetable 

 spores. 



When I made my observations on the Torrea^ I sought 

 with the greatest care to discover whether there were any 

 envelope around the masses destined to be resolved into sper- 

 matozoids, and notwithstanding their unusual size in this worm 

 I have never been able to perceive the least trace of such a 

 covering. Neither have I been able to distinguish the walls 

 of cells during the division. Since that time I have, many 

 times, instituted researches of the same kind, and invariably 

 with the same result. The spermatogenous masses have 

 always appeared to me to be composed of a perfectly homo- 

 geneous substance, and never to present any indication of a 

 cell-nature. 



If to these observations are joined the positive facts which I 

 have pointed out in the vitellus of worms and of the mollusca, 

 the negative results which I have just recorded acquire, as it 

 seems to me, a real value. Thus the cell-theory had been 

 applied, very happily as it seemed, to the segmentation or 

 division of the vitellus; but this doctrine necessarily suc- 

 cumbed before the fact that the most marked lobes, those in 

 which both the nucleus and the cell could not fail to have 

 been the best characterized, spontaneously fuse into one 

 another. If, then, theoretical conceptions are discarded in 

 favour of observation, the views which I have just explained 

 will I hope be adopted ; and it will be acknowledged that in 

 this case at least the cell-theory should be abandoned. 



On the Influence of Dilute Sulphuric Acid on the Deposit 

 Layers of the Cell-wall in its earliest condition. By Dr. 

 T, Hartig. (Botan. Zeitung, March 30, 1855, p. 222.) 



In a previous paper in the same journal the author has shown 

 that the continued multiplication of cells in the ligneous and 

 alburnum layers, is effected by a twin pair of parent-cells 

 belonging to each fibrous ray, the inner one of which throws 

 off a series of sterile secondary cells towards the medulla, and 

 the outer a similar series towards the bark. 



Each of the parent-cells, which correspond in size, form, 

 and structure, consists of a thin cell-wall and a double 

 ptychode-sac ; the cell-wall itself consists of an internal and 

 of an external cell-membrane, between which is deposited a 



