Dr. J. E. Stocks on the Structure of Cucurbitaceae. 113 



the inflected sides of the carpels and lie imbedded each in their 

 own cell. 



3. In Citrullus Colocynthis and others, when we carefully dis- 

 sect off the rind of the fruit, we find the placenta? forming a con- 

 tinuous line from the top to the bottom, perfectly free from any 

 attachment to the rind or to the pulp, and splitting down the 

 centre without force so "as to divide each placental dissepiment 

 into two. 



It may be remarked that the three columns of pulp in Coc- 

 cinia indica, which Dr. Wight regards as representing the car- 

 pellary leaves, are each divided into two other columns by a 

 double line of vessels (the primary dissepiments) which can be 

 traced following the usual involute direction and end in the pla- 

 centae. 



Style and Stigma. — In the style the carpellary leaf has an 

 induplicate aestivation, leaving in many cases a style-canal. The 

 style-column diverges into its three parts, and each of these ends 

 in two stigma-points which are connected by a crescentic line of 

 stigmatic tissue looking outwards. The styles are opposite to 

 the seminiferous, and alternate with the primary dissepiments ; 

 and the stigma-points when close together are immediately on 

 each side of the secondary or seminiferous dissepiments ; but when 

 much diverging, those of adjacent carpels are close together and 

 opposite the primary dissepiments. 



Arillus. — A seed is said to have an arillus when the paren- 

 chyma in which it is imbedded becomes pulpy and adheres to its 

 surface ; but the term should be cancelled if we regard the origin 

 of the part, for it does not grow from the placenta over the seed, 

 but is merely the cellular tissue in which it nestles. In Luffa 

 and Citrullus it is a mere scarious membrane which soon peels 

 off; in Coccinia, Momordica, Trichosanthes, a red pulp ; in Pilo- 

 gyne a gelatinous nidus. 



Examining Coccinia when half-ripe we find vascular parch- 

 ment-cells, inside which are the seed and a waxy substance which 

 afterwards becomes the soft arillus, while the parchment-layer 

 with its vessels becomes flexible and offers no resistance to the 

 separation of the seeds. In Luffa, the layer to which the vessels 

 are more immediately attached remains dry and membranous in 

 the lignified pepo, and it is chiefly the epidermis of the carpellary 

 leaf which becomes the filmy fugacious covering of the seed. 



In Trichosanthes again the pulp breaks up, and a portion ad- 

 heres to each seed, in which we can trace the vascular layer of 

 the carpellary leaf, and internal to it the pulpy layer, and more 

 internal still a thin membrane, which we may regard as the epi- 

 dermis or that part which is seen covering the seed of Luffa. 



