i;Y.MXOSPEKM.. 



4. The number of carpels in each flower varies from one to 

 many, most frequently three, of which the central one remains 



sterile. 



5. Each carpel bears only one ovule. The flower which is 

 formed of only one carpel appears to consist of only one ovule. 



'-. The ovule has in Taxaceee either a double integument 

 (Podocarpese, Taxea>), of which the external is the "aril," or, as 

 in the Cycadea?, a single one, which is homologous with the two 

 united together. 



7. The external integument in the Pinoidea? is expanded to 

 form a leaf-like structure the ovuliferous scale and bears on its 

 dorsal side the ovules, which are thus only provided with one, and 

 that the inner, integument. 



This later interpretation of the female cones in the Coniferae is more pro- 

 bably correct than the older ones ; that, however, which appeared in the former 

 issues of this book, may also be stated. It was to the effect that each catkin- 

 like female cone is in reality a single flower ; the cone-scales in the Cupressaceae 

 were single leaves, namely carpels, which bore the ovules on the side which is 

 turned upwards ; the division into two parts which makes its appearance in the 

 other orders, and becomes most prominent in the Abietacerc, was compared 

 with the division of a leaf into a barren and a fertile portion, which is found 

 especially in Ophioglossaceas and Marsiliacese, or with the ligule in Isoetes. 



POLLINATION is accomplished by means of the wind. At the 

 period of pollination the leaves are always so widely separated 

 from one another, that the ovules can catch the pollen-grains 

 carried to them by the wind; this is often effected by the mucila- 

 ginous drops which appear at the micropyle, and by the evapo- 

 i at inn of which the pollen-grains are brought in contact with 

 tin- nucellus. The entire cone grows considerably as soon as 

 fertilisation has taken place, and the cone-scales in Pinoidea? 

 cloSe together so that the seeds while maturing are enclosed, and 

 it i> not until the seeds are ready for distribution that the cone- 

 scales again become separated. In the Pinoidea-, the fully deve- 

 loped ovuliferous scales are hard and woody ; and in this condition 

 tin- collection of female flowers is termed a cone. In the Taxoidece, 

 true cones are the exception. 2-15 cotyledons are present, ar- 

 i-an-vil in a whorl. 



''In- '-liararteristic feature of this class is the abundance of 

 which is to be found in isolated cells (especially in the 



