Some Observations in the Life History 



of Isoefes, 



(Contributions to Cytology and Genetics from the Departments 

 of Plant-Morphology and of Genetics, Science College, Tokyo Imperial 

 University. No. 39.) 



By 

 Noboru Takaiuiiit'. 



{IVit/i g Text- figures) 



Since Belajeff's work (1) on antheridia and sperniatozoa of 

 Isoetes appeared in 1885, Farmer (6), Campbell (3) and others 

 have made the study on the development of microspores and macro- 

 spores of Isoetes, but our knowledge of the life history of Isoetes 

 seems still far from being complete. It may not be out of place to 

 give here a short note on this subject from the writer's own obser- 

 vations. 



Materials and Methods 



The materials used in this study were Isoetes japonka and I. 

 asiatica. I. japonica is widely distributed in Honshiu of Japan, while 

 I. asiatica is rather limited to certain localities. 



The former species, which is the one commonly used in the 

 laboratory work in this institute, was collected in the suburbs of 

 Tokyo, and the latter in Nojiri lake in Nagano prefecture, where it 

 is found in abundance. 



For fixing the spores, I have tried Flemming's stronger solution, 

 Bouin's solution, and Hermann's platinum chloi-ide osmic acid solution ; 

 and tlie latter was found to serve the purpose best. Microtome- 

 sections were made 10/< thick for microspores and 15 to 20// thick 

 for macrospores ; they were stained with safranin and Heidenhain's 

 iron-alum haematoxylin. 



Before the spox-es reach their maturity, they are to be freed from 



