670 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



in Cryptogams, Gymnosperms, and Monocotyledons. Stipular-struc- 

 tures are leaf-like expansions which arise from the leaf base. They 

 may occur either in the form of a sheath or as lateral appendages 

 (stipules) of the leaf base. The author regards the sheath as the 

 original form of stipular-structure, and considers that the paired 

 stipules are derived from the sheath by the abortion of the sheathing 

 part and the survival of the wing-like side-lobes of the former sheath. 



The petiole of the leaf is also regarded as a secondary structure 

 which can be derived either from the sheath or from the blade (lamina) 

 of the leaf. 



Among the vascular Cryptogams the sheath is the only form of 

 stipular-structure to be found, although in the Marattiaceae the 

 lateral appendages of the sheath closely simulate a pair of stipules. 

 Among the Gymnospermae, Gnetum, Gingko, and the Cycads possess 

 stipular-structures in the form of sheaths. Among the Monocoty- 

 ledons the sheath is the prevalent and original form of stipular- 

 organ. In a few cases the sheath itself is so reduced and modified 

 that the resemblance of the structure to a pair of stipules is very 

 strongly suggested {e.g., Potamogeton species, Najas, Smilax otigera). 



In Tamus hair-structures (trichomes) simulate free stipules. 



Among the Dicotyledons the author also believes that the majority 

 of the free lateral stipules are only the side-appendages of an aborted 

 sheath. In a few case, however, they may possibly have a direct 

 origin independent of a sheath, but such cases will, beyond doubt, 

 be found to be very rare. 



Domin points out that, according to these views, a leaf with an 

 aborted sheath, and with side- appendages alone surviving, indicates 

 a higher state of morphological differentiation than one in which the 

 stipular-organ is represented by a sheath. Since the latter condition 

 is characteristic of the Monocotyledons, and the former is more com- 

 mon amo'ug the Dicotyledons, it follows that the Monocotyledons 

 possess a more primitive form of leaf than the other great division 

 of flowering plants, and this fact may be of significance in discussing 

 the relative antiquity of the two groups of plants. 



It is impossible in this abstract to indicate the wealth of details 

 which is contained in Domin 's paper. For these the original must 

 be consulted. — R. B. 



Stocks, Doubleness in. By Miss E. E. Saunders (Jour. Gen. 

 i. pp. 303-376). — In this long paper Miss Saunders gives an account 

 of the extensive series of experiments she has carried cut in attempting 

 to unravel the mystery of doubling in flowers ; and, although the 

 phenomenon is by no means solved, one or two facts have been brought 

 to light that should be of great importance to the plant breeder. She 

 finds that all sap-coloured races of ten-week stocks so far investigated— 

 azure, light purple, dark purple, marine blue, flesh, copper, red, and 

 two non-sap colours, white and cream — ^have two forms, an ever- 

 sporting one which continually throws doubles in greater proportion 



