2 Miyake, The development oi the gametophytes etc. 



gaps left by Arnoldi and thus to complete, as far as possible, 

 the histoiy of the gametophytes and emhryogeny of the genus. 



Cunninghamia sinensis, which was the onl}^ meniber of the 

 genus, until the recent discovery in Formosa, disclosed the presence 

 of a sister species C. Kofiishii (Hayata, 1908), is a native of 

 China and is found in Japan only in the cultivated condition. The 

 material for the present study was collected chiefly by myself 

 during the last four years 1905 — 1908 fi'om plants growing in 

 Kyoto and Tokyo. A few materials which had been collected by 

 Prof. K. Shibata before the year 1905 and kindly given to nie, 

 were also examined. 



The material was obtained from different trees, and from 

 several cones of the same tree at each coUection, and the fixing 

 was done immediately after the collection. The staminate cones 

 were fixed entire or cut into several pieces according to their sizes. 

 In the early stages of development the ovules were fixed with a 

 part of the scales, and later the ovules were entirely i-emoved 

 from the scales. For older stages, a part or the whole of the 

 integument was removed before fixing. 



Flemming's chrom-osmo-acetic acid Solution of various con- 

 centrations was chiefly used for fixing, but chrom-acetic mixture 

 was also occasionally used. After fixing, the material was washed, 

 dehydrated and imbedded in paratfin in the usual way. The sections 

 were cut usually from 5 to 10 /t in thickness. For staining, 

 Flemming's safranin, gentiau violet, and orange combination or 

 Heidenhain's iron-alum haematoxylin were used. 



Development of the Pollen. 



The staminate cones make their appearance, at or near the 

 tips of the branches, as early as September of the year preceding 

 pollination. The mature cones at the time of poUination is shown 

 in text-flgure 1. Young microsporangium, as observed in early 

 November, has the wall consisting of two or three layers of cells 

 and just within, in immediate contact with the archesporium, there 

 is a layer of tapetum-cells. The archesporial cells are found in 

 constant division dui'ing the autumn and the poUen mother-cells 

 are formed before the end of the year. 



The division of the pollen mother-cell takes place (in the 

 middle part of Japan) about the end of February or the begiuning 

 of March. The pollen mother-cell, whose nucleus is in a resting 

 condition, is shown in Fig. 1. As the cell prepares for division, 

 the Contents of the nucleus undergo a synaptic contraction (fig. 2). 

 Then follows the spirem stage (fig. 3). The thin spirem thread 

 gradually thickens itself and the double nature of the thread be- 

 comes more or less apparent (fig. 4). The thick spirem now 

 Segments into chromosomes (fig. 5). The stages between synapsis 

 and chromosome-formation are now considered as the most important 

 phases in the reduction-division, and have been investigated with 

 special care by several cytologists during last few years. The 



