202 
CONTRIBUTIONS TO BOTANY. 
repeat that this definition is founded upon misconception, or on 
too much faith in the erroneous descriptions of Mirbel and 
St. -Hilaire, 
Dr. Fritsche (in 1835) was the first who impugned in part the 
accuracy of MirbeFs observations on the development of the 
ovule in Cucurbita. Mirbel had described the first indication of 
the growing ovule as a simple cylindrical shoot protruding from 
the placenta, which after a while exhibits a point, somewhat ex- 
centrieally placed near its apex, out of w'hich the nucleus forces 
an opening; this nucleus continues to grow, becoming sur- 
rounded at its base by an annular ring, the rudiment of the 
secundine, while the lacerated opening out of which the nucleus 
springs forms the mouth of the primine and gives I’ise to 
the outer coat of the ovule. Fritsche confirms the accuracy of 
the ajipearances thus described, but contends* that the nucleus 
does not originate in a sort of coleorhizal protrusion as narrated 
by IMirbel, but that the whole placental shoot in question is in 
reality the nucleus upon its funicular support, before any indi- 
cation of the primine and secundine : this shoot is covered by a 
single epidermal layer of cellular structure; and at some little 
distance from its extremity a double circular constriction is 
formed, thus leaving a prominent annular ring round the pa- 
pilla, which remains as the nucleus, while the portion of the 
epidermis between the two strictures separates from the internal 
parenchyma and becomes plicated, so that its folded surfaces 
unite together in the form of a short tube, thus giving origin to 
the future secundine. Subsequently that portion of the epi- 
dermis below the strictures also separates and becomes folded 
in like manner, thus giving rise to the future primine. This 
assumption of the separation of the epidermis I believe to be 
quite erroneous, for reasons presently to be given ; and it will 
be seen that, in regard to this early stage in the development, 
Mirbel was nearer the truth than his opponent. 
Schleiden, although he seems to have adopted the erroneous 
views of Fritsche concerning the earliest origin of the nucleus 
and ovular tunics, gave (in 1843) an account of their subsequent 
development and growth, somewhat different from that of Mir- 
bel : he saysf, “The funiculus is much elongated, the nuclear 
papilla bends downwards; and thus the side, either of the naked 
nucleus or of the simple or of the external bud-integument 
(secundine or primine), turned towards the funiculus, becomes 
blended with it. In the perfect seed-bud the nuclear papilla 
then lies close to the point of attachment, the chalaza opposite 
* Wiegmann’s Archiv, i. 2 Band, p. 229. 
t Principles of Scientific Botany, Engl. edit. p. 390. 
