1880.] 



MICKOSCOPICAL JOUKNAL. 



235 



stomata are all situated in the part 

 of the epidermis touched by the 

 chloroj)hyll bearing parenchyma, 

 which is readily distinguished upon 

 the exterior of the stem as inter- 

 rupted lines of darker green. 



The fibro-vascular bundles are 

 open, two-sided bundles, but pecu- 

 liar in having an additional phloem 

 portion on the axial side. The 

 xylem and the outer phloem are se- 

 parated by the cambium, in which 

 the progressive transformation from 

 simple uniform cells to the various 

 mature cells of each portion can be 

 traced. Both the axial and outer 

 phloem consist of sieve-tubes, inter- 

 spersed with long, slender parenchy- 



ma cells, the two together forming 

 " soft bast." These are excellent 

 examples of sieve-tubes : the per- 

 forated end-partitions, the broad 

 thin spots and sieve-plates of the 

 side walls, and the conspicuous pro- 

 toplasmic contents are readily made 

 out in detail. The xylem contains 

 all gradations between the extreme 

 form of annular vessels with widely 

 isolated rings, on the one hand, 

 through spiral, reticulated, scalari- 

 form, to pitted vessels, on the other 

 hand. The structure of the walls 

 of these vessels can only be studied 

 satisfactorily under high powers. 

 Between and about the vessels is 

 wood-parenchy m a. 



To sum up the Tissues of the stem of Cttcurbita 



Epidermal system : 

 Epidermis. 

 Stomata. 

 Hairs. 

 Fundamental system : 



Interfascicular parenchyma. 

 Hypoderma. 



Cortical wood. 



Cortical parenchyma. 



Collenchyma. 



To these should doubtless be ad- 

 ded laticiferous tissue sometimes 

 detected in the phloem. It will be 

 observed we have illustrations here 

 of the three tissue systems ; of all 

 the principal sorts of tissues, except 

 sclerenchyma, i.e.^ parenchymatous, 

 fibrous, laticiferous, sieve, and tra- 

 cheary tissues ; with several well- 

 marked varieties of the first and 

 second. The only prominent va- 

 rieties not included are cork, bast, 

 and tracheides, modifications res23ec- 

 tively of parenchymatous, fibrous, 

 and tracheary tissues. It would 

 probably be difiicult to select any 

 one common example that more 

 admirably illustrates tissues and tis- 

 sue elements, and, withal, so simply 



Fibro-vascular system : 

 (Cambium). 

 Phloem. 



Sieve-tubes. 

 Phloem parenchyma. 

 Xylem. 

 Vessels. 

 Annular. 

 Spiral. 

 Reticulated. 

 Scalariform. 

 Pitted. 

 Wood parenchyma. 



constructed for histological study. 

 J. C. Akthur, 



University of Wisconsin. 



EDITORIAL. 



— To. all our readers we extend a 

 hearty Christmas greeting, and our 

 best wishes for a happy and a pros- 

 perous I^ew Year. 



o 



— The success which has resulted 

 from our efliorts to establisli a 

 monthly journal devoted to micros- 

 copy, during the first year of its 

 existence, has far exceeded our an- 

 ticipations ; and we are pleased to 

 state that the success of this Jour- 



