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observations commit oversights. Those peculiar formations 

 on the epidermis of the leaves of Pleurothallis, the closing of 

 which by means of a cross septum had escaped me, and had 

 thus given a false indication of their probable design, originate 

 in simple petiolated glands, which first appear as simple cells of 

 the cellular layer situated immediately beneath the epidermis. 

 The epidermis is in these cases actually broken through, even 

 the cuticle accompanies the surface of the funnel-shaped hol- 

 low, which has originated in this rupture, far down into the 

 hollow, but not to the bottom, as M. Schleiden has repre- 

 sented it. Just as in other cases similar ruptures in the cel- 

 lular layer of the epidermis are closed by epidermal glands 

 with their stomata, so in Pleurothallis the closing of these 

 funnel-shaped ruptures is accomplished by means of the sim- 

 ple glands. At its first appearance on the young leaf the 

 gland presents itself as a simple cell, which is only a little 

 longer than the vertical height of the cells of the epidermis, 

 and at the end projecting beyond the surface of the epidermis 

 is swollen into a club : its form is then similar to the gland of 

 Helleborus fcetidus. This club-shaped swelling subsequently 

 separates by the formation of a diagonal septum, which still 

 remains for some time as a vesicular cell, sometimes it is divided 

 a second time by a longitudinal partition, but subsequently 

 always falls off, upon which the peduncle remains in the 

 funnel-shaped rupture of the epidermis, and its cellular sep- 

 tum subsequently becomes intimately united with the sur- 

 rounding surface of the cuticle. Not unfrequently this cell, 

 which has served as a pedicel, divides again by the formation of 

 diagonal walls into two or even into three smaller cells, which 

 latter case however is very rare. The secretion of an oily sub- 

 stance takes place more or less abundantly in the remaining 

 pedicels, as also in the contiguous cells ; and the peculiar ar- 

 rangement of some small cells around the base of the glan- 

 dular pedicels (which always originate from the subsequent 

 separation of the larger) is similar to that which occurs at the 

 base of many hairs, where they are raised with these above the 

 surface of the plant. I also found on a very young leaf an 

 entire glandular apparatus, such as is commonly situated be- 

 tween the cells of the epidermis of Pleurothallis, projecting 

 beyond the surface of the leaf. 



