

sept. i9io.] FUJIL- . r JlABKS ON THE CRET. FLORA ETC. 219 



were available for I study of general phylogeny, and on the 

 other hand, if we could find any signs or conditions of the 

 dying out of the plants of archaic type and the cause of the 

 dominant display of the modern plants. 



Ishikawa (M. Ishikawa, Cytologische Studien von Dahlien. 

 1910. Manuscript.) in his cytological study of Dahlia, expressly 

 pointed out among other things, the possibility of close rela- 

 tions between the remarkable manifold ness of forms in Com- 

 posite and the large amplitude of fluctuations of chromosome 

 numbers, which range from 3 to 32 (number of gemini). Now 

 when we turn to the lower type of seed plant, Gymnospermas, 

 it was well known among the authors engaged in the cytologi 

 cal study of Coniferse, that the number of gemini in the meiotic 

 phase or of chromosomes in the post meiotic phase is as a rule 

 12 ; e.g., Miyake in his recent studies of Cunninghamia (1910) 

 states ' This number, i. e., that of the bivalent chromosomes is 

 twelve, as it is usually the case with other conifers.' Also 

 Robertson pointed out, in passing in her paper on Torreya 

 californica (1904) the number 12 as characteristic to Conifers 

 other than Taxus and Torroya (?). Certainly there are a few 

 exceptions, where the number of chromosomes were reported 

 otherwise ; e.g., 8 in Taxus (Strasburger, 1904) and Sciado- 

 pitys (Lawson, 1910), 9 or 10 in Cryptomeria (Lawson, 1904), 

 8 (?) in T or rey a californica (Robertson, 1904), etc: But they are 

 of a small number among known cases of chromosome numbers 

 in Coniferse, and are mostly doubtful cases, which must be Care* 

 fully reexamined. 



With regard to Ginkgo, Dr. M. Ishikawa has on my request 

 kindly examined the number of chromosomes in the meiotic 

 phase Jof the division of pollen mother cells with the materials, 

 which were collected in the last spring by himself and Mr. 

 Kawada ; and ascertained that the number of chromosomes 

 was 12.ro 



Among the Cycadales I may mention a few known exam- 

 ples : 12 chromosomes in Dioon edule (Chamberlain, 1906 and 



(1) An account of this observation with figures will be given by him in the 

 next number of the present journal. 



