814 SUMMARY OF CURRENT RESEARCHES RELATING TO 



cellular spaces, and of the fibre-vascular bundles, usually collected 

 together into groups, often in long longitudinal bundles. They are 

 greatly elongated cells, from 0'5 to even 13 mm. in length, and from 

 0*025 to 0*06 mm. in diameter, and occasionally are even branched. 

 They contain nothing but air, and are surrounded by ordinary paren- 

 chymatous cells. Their form and disposition differ in other species 

 of Crinum, but are nearly uniform in the same species. They were not 

 found by M. Trecul in any part of the plant except the leaves ; but 

 M. Mangin finds them also in the cortical tissue of the stem, where 

 they attain a still greater size. M. Mangin considers them as 

 analogous to internal hairs. 



In Nepenthes phyllamphora similar cells occur in the stem, the 

 leaves, and the pitchers, but always isolated. The parenchyma which 

 contains them is here compact, and not furnished with intercellular 

 passages. 



Structure of Secretory Glands.* — An examination of the internal 

 glands in a large number of plants has led Dr. P. It. v. Hohnel to the 

 following general results : — 



The glands of the Myrtacese, those Leguminosae which were ex- 

 amined (Amorpha, Hymenea, and Trachylobium), the Hypericinese 

 (Hypericum and Androsoemum), and of Oxalis, Lysimachia, Myrsine, 

 Ardisia, and Peganum Harmala are schizogenous ; while (except 

 Peganum Harmala) those of the Eutacese and their allies (Callionema, 

 Citrus, Toddalia, Boronia, Correa, and Ptelea) are lysigenous. 



The secretion-cavity is always completely closed in lysigenous 

 glands : while in schizogenous glands there are three distinct 

 varieties : — (1) completely closed, which is the ordinary case ; (2) 

 those which at length burst from the copious excretion of fluid 

 {Oxalis floribunda) ; and (3) altogether open ; these are properly only 

 secretory portions of ordinary air-containing intercellular spaces 

 (Peganum Harmala and Lysimachia ephemera). 



Glands which are buried in the tissue are either entirely dermato- 

 genous (Amorpha, and those Myrtacesa where the glands are im- 

 mediately beneath the epidermis), or are in their outer portion formed 

 out of the epidermis (Citrus, Dictamnus, and probably Correa, Toddalia, 

 and many other genera of Rutacese), or their origin is altogether 

 independent of the epidermis (all deeply buried glands, as those of 

 Eucalyptus, Hypericum, Ardisia, Myrsine, &c). Lysigenous glands 

 appear to be generally formed from several cells which have become 

 separated before the first appearance of the gland (Callionema and 

 Citrus) ; while schizogenous glands are almost always formed from a 

 single cell (Myrtacese, Lysimachia, Hypericum, and Myrsine), very 

 seldom from several (Amorpha). 



When mature the distinction between schizogenous and lysigenous 

 glands is always observable. The former always have an epithelium 

 sharply defined on the inside, and usually more or less clearly dis- 

 tinguishable from the surrounding cellular tissue by the nature of 

 the cell-wall and of the cell-contents ; it is from this that the fluid 



* SB. K.K. Akad. Wiss. (Wien), lxxxiv. (1881) pp. 565-603 (6 pis.). 



