334 MESSKS. CYEIL WEST AISD H. TAKEDA ON 



depression is formed in the caudex, tliere is a cluster of short immature leaves, which 

 will develop in the following season (PL 33. figs. 7, 8 ; PI. 34. fig. 10). 



It is generally stated (3, p. 34 ; 6, p. 563 ; 27, pp. 757-8), that in Isoetes the outer- 

 most leaves of the ' rosette ' are megasporophylls *, and that these are followed hy a 

 cycle of microsporophylls whilst the innermost zone is made up of sterile leaves. This 

 statement, however, is incorrect. In /. jajponica the sterile leaves, which form the 

 transition from one year's increment to the next, are found on the periphery of the 

 ' rosette.* The mega- and micro-sporophylls are not arranged in any definite order, hut 

 are irregularly distributed throughout the wide zone of fertile leaves. When a plant 

 is dug up late in the year, it often happens that the sterile leaves of the outermost whorl 

 of the rosette have hy that time completely decayed away ; under these circumstances 

 sporophylls are found on the margin. But if such a leaf -rosette be carefully dissected, 

 young sterile leaves will be found in the centre; these are generally regarded as 

 belonging to the present season's growth, but actually they represent the outermost 



cycle of next year's rosette. 



The sporangia are elliptical or narrowly oblong and are embedded in the fovea, the 



margin of which docs not project as a velum. 



A well-developed ligule is borne just above the fovea. The ligule is ovate-lanceolate, 

 cordate at the base, and elongate-acuminate towards the apex (PL 36. figs. 25, 26, 27, 

 83). In a small specimen the length of the ligule is about 3 mm., but in a large plant 

 a length of nearly 15 mm. is reached, whilst the width may exceed 5 mm. 



Material and Method. 



The material used in this investigation was collected near T6ky6 by one of us m 

 September, 1913. Plants of all ages (several weeks to many years old) were represented. 

 The larger specimens were collected from a fairly rapid stream some 3 feet deep, wbilst 

 the smaller plants were gathered from narrow ditches where the water was very shallow. 

 Ul the specimens were preserved in alcohol (about 75 per cent.). 

 Sections were cut either by microtome or by hand, and were mounted in Canada 



Balsam or in Glycerine- jelly to which various stains had been added. Por the general 



I 



work we employed the Safranin-Hsematoxylin combination, but for special purposes 

 several other stains and reagents, including Azo-blue, Corallin-soda, Gentian-violet, 



Phloroglucin, Chlor-zinc-iodine, Iodine-sulphuric acid, and Sudan III were found useful. 



General Anatomy or the Caudex. 



We have nothing to add to the existing accounts of the structure and development 



of the very young sporophyte of Isoetes, the anatomy of which has been carefully 

 studied by Hofmeister (16), Bruchmann [7), Farmer (14), and Campbell (10). The 

 conclusion c^enerally arrived at is that the axile stele of the young sporophyte is made 







Milde (23, p* 275), on tlie otlier hand, states that the outermost leaves are microsporophylls 



