284 DR, M. J. SCHLEIDEN ON PHYTOGBNESIS. 



structure is mostly granular, without however the granules of 

 which it consists being clearly distinct fi-om one another. Its 

 consistence is very various, from such a softness that it almost 

 dissolves in water, to that degree of finnness that it bears even 

 the pressvu-e of the compressorium without losing its form. The 

 nearer it is to its origin the softer it is, and also where its ex- 

 istence is merely transitory. It is denser and more sharply de- 

 fined where it goes through the whole vital process of the plant 

 as a permanent tissue, as in the Orchidece. 



These peculiarities have been more or less completely de- 

 scribed by R. Brown (Organs and Mode of Fecundation in Or- 

 chidete and Asclepiadeie; Linn. Trans. 1833*, p. 710) andrecently 

 by Meyen {Physiology, &c., vol. i. p. 207) . But a circumstance has 

 escaped these two most acute obsei-vers, which I nevertheless 

 am inchned to place amongst the most essential. In very large 

 beautifully developed cytoblasts, for instance in the recently ori- 

 ginated albumen of Phormium tenax and Chamesdora Schiedeana 

 (Plate t XV. fig. 5), there is observed (whether sunk in the in- 

 terior or on its surface was not evident to me) a small, sharply 

 defined body, which, judging fi-om the shadows, appears to repre- 

 sent a thick ring or a thick-walled hollow globule. In less deve- 

 loped individuals only the outer sharply defined circle of this 

 ring can be observed, and in its centre a dark point, for instance 

 in the stipes of the embryo of Limnanthes Douglasii, Orchis 

 latifolia (PI. XV. fig. 21), Pimelea drupacea (fig. 14, 15). In 

 still smaller cytoblasts it appears merely as a sharply circum- 

 scribed spot ; this is most frequently the case in the pollen of 

 Richardia (Bthioptca, in the young embryo of Linum pallescens, 

 and in almost all Orchidece (fig. 16). Or lastly, there is observed 

 only a remarkable small dark point. In the very smallest and 

 most transitory cytoblasts (for instance in the leaves of Dicoty- 

 ledons) I have hitherto not been able to discover it. In very 

 rare cases, and those probably mere exceptions, and always only 

 where the majority exhibited the simple nucleus, I have also 

 found two; for instance in Chamesdora Schiedeana (fig. 6, 7) 

 Secale cereale, Pimelea drupacea (fig. 14) : — in the two latter Ij 

 have found sometimes even three (fig. 15). From my obser 

 vations on all plants which admitted of a complete watching o; 



* Read at the Linnsean Society Nov. 1, 1831. 



■f- The Editor has been favoured, through the kindness of Dr. Schleiden, with 

 impressions from the copper-plates engraved under his superintendence. Having 

 been printed abroad, the numbers have not been placed on the plates, but they 

 are referred to in this work as Plates XV. and XVI. 



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