174? Dr. Schleiden o?t the Development of the 



In this manner has the doctrine of metamorphosis or the 

 morphological design of the organs of plants gradually formed 

 itself into a peculiar department of scientific botany j and at 

 the same time that it has offered a field for the exertions of 

 the most celebrated men, upon which they have obtained 

 lasting honour, it has become the appropriate theatre for all 

 friends of enigmas, dreamers, and dealers in paradoxes, and 

 has served for the display of the most vi^onderful things, 

 which have been unhesitatingly dignified with the proud 

 name of Philosophy or Speculation. Speculation, however, 

 is only admissible where our means of observation fail us ; 

 and if it thrusts itself forward, desirous of taking the place 

 of observation, we should do wisely to get rid of it as a tire- 

 some guest. How much might we be in advance of our pre- 

 sent position, even in the speculative sciences, were it not that 

 speculation devoted itself to objects, which, consuming its best 

 time and best powers, not only did not require it, but would 

 even have been better without it I It is precisely in the history 

 of development that examples of this sort are particularly 

 frequent. If therefore the prosecution of this branch of science 

 shall attain importance and become established in all its 

 parts, it will not suffice that investigations be commenced on 

 a bean or something of that sort which may conveniently be 

 dissected with a penknife ; a much earlier period must be 

 chosen, that of the first origin of the embryo. A ripe 

 seed presents the young plant already provided with such 

 manifold organs, that a wide field is here opened to mere 

 speculation sufficiently extensive to render subsequent inves- 

 tigations vague and unprofitable. 



Upon its first appearance the embryo is recognised as a mem- 

 branous cylinder (PI. III., fig. 9 & 13) rounded and closed su- 

 periorly, but open inferiorly, since the membrane constituting 

 the embryo is invariably continued into the sac containing it 

 (appearing indeed to be merely a reduplication of that sac) 

 and filled with an organizable, for the most part pellucid fluid 

 mass, which becomes gradually converted into cells, begin- 

 ning from above downwards, (fig. 6 & 10) during which pro- 

 cess the cellular nuclei also become apparent (fig. 12 & 24), 

 which appear at all times to perform a principal part in the 

 formation of cells. At this point a leading phaenomenon in 

 vegetable life finds its explanation. The embryo originally 

 consists of axis alone, and being closed superiorly, only al- 

 lows a further development from within outwards, but is not 

 limited inferiorly ; and by the secretion of organizable matter 

 becoming transformed into cells, admits of unlimited prolong- 

 ation ; whence not only the direction but the mode of growth 



