PAMMEL — O.V THE SEED-COATS OF EUPHORBIA. 5/^5 



ined the seed-coats of the following Orders : yuncacece, Liliacece^ 

 Iridacece, AlismaceiC. Bctulacea:^ Ciipiilifcrce^ jficglajzdacece, 

 LegiuninoscB^ Rosacece^ Granatecc^ Rhaninacctv^ Cucurbitacece^ 

 AraliacecE^ CaryophyJlacecc^ Nvmphceacece^ Ramincnlacece^ 

 Afagnoliacece, Berberidacecc^ Papaveracecv^ JFuniariacea;^ Am- 

 pelidece^ Celastracece^ Sapi7idacc<x^ Linacece, Ilicinccc^ Plaiita- 

 ginacea:. Caprifo/iacccc. As a result of his work he concludes 

 that little aid can be obtained from such studies. He states that 

 the seed-coats of closely related genera and species differ but 

 little. In some suborders like A/agnoiiea; slwA I/tcccv of the ^Icig- 

 noliacecc; and Siloiccc and Ahinecc of the Caryophyliaccce^ suf- 

 ficient structural differer.ces occur to separate them. 



Ewald Bachman,^ m his excellent paper on the development 

 and structure of the seeds and the seed-coats of ^'cro^^z^/arzaccf^, 

 considers the microscopic structure of the seeds of only condi- 

 tional value from a systematic standpoint. It is true he says that 

 in the section Cymbalaria of the genus Linaria the seeds are- 

 provided with reticulated thickenings (netzfaserschicht) found in 

 no other seeds of the genus, but the same structure again occurs 

 in other genera not closely related, where the dehiscence and 

 structure of the capsule is the same as in PeJitstemon digitalis. 

 Biiddleiece is clearly separated from all other tribes of the Scro- 

 phiilariacecc, yet the seed-coats do not differ in any marked 

 degree from those of Pcdiciilaris pahistris. 



The seed-coats of Euphorbiacecc have been studied but little, 

 and those of Euphorbia still less. Gris,^ who studied the devel- 

 opment of the seeds in Euphorbia., found two seed-coats present. 

 Poisson^ made more extended study of the seed-coats of ^?/^/^cr- 

 biacecc. He finds that different species and genera differ greatly 

 in regard to the number of layers of cells found in the outer and 

 inner seed-coat. Several genera of Euphorbiacece have been 

 the subject of exhaustive treatises ; thus Ricintis has been stu- 



5. Die Entwickelungsgeschichte und der Bau der Samenschalen der Scrophularineen. 

 Inaugural Dissertation (separate from K. Leop.-Carol. Acad, der Naturforscher, voU 

 xliii. Halle, iSSo, 4 Plates), pp. 179. 



6. Ann. Sci. Nat. Ser. 4, vol. xv. No. i, p. i; vol. xvii., 1S62, p. 315. 



7. Bull. Soc. Bot. de France, 1S7S, p. 47. 

 V-— 3— 14 



