404 



INTRODUCTION TO CYTOLOGY 



and produce 32 reduced spores (Fig, 227, B). The reduced number 

 here (60 + ) is doubtless a polyploid one. 



2. Unreduced Apogamy. — The developing cells have nuclei with 

 the unreduced (zygotic) chromosome number. 



[Called diploid apogamy by Hartmann, somatic apogamy by Winkler and Ernst, 

 diploid apogamety by Renner, and euapogamy by Farmer and Digby.] 



This type of apogamy appears to occur in certain ferns. In one 

 reported case^ the sporophyte arises from unreduced "engrafted tissue" 



Fig. 227. — A, nuclear abnormality in sporangium of Aspidmm falcatum. {After 

 R. F. Allen, 1911.) B, restitution nucleus in Nephrodium hirtipes. {After Steil, 1919a.) 



C, unreduced parthenogenesis and sporophytic budding in embryo sac of Alchemilla 

 pastoralis. The egg is developing one embryo below and a nucellar cell is forming another 

 above; two polar nuclei and one synergid nucleus at middle. {After Murheck, 1901.) 



D, gametophyte with antheridium and rhizoids arising aposporously from tissue of sorus 

 in Polystichum; sp., sporangia. E, gametophyte with archegonia arising from tip of 

 pinnule in Polystichum. {D and E after Bower.) 



which develops after a nuclear migration and fusion in certain cells of 

 the reduced gametophyte (Fig. 226, .4), Such a fusion in cells not 

 specifically organized as gametes has been called pseudomixis. In angio- 

 sperms the formation of embryos by unreduced synergids or antipodal 

 cells has been reported,^ but the cytological data in most such reports are 

 rather scanty. 



C. Sporophytic Budding. — The formation of new sporophytes by 

 sporophytic cells surrounding the embryo sac, such cells projecting into 

 the sac and developing into embryos. Commonly the cells in question 



^ Lastrasa pseudo-mas, var. polydactyla (Farmer, Moore, and Digby, 1903; Farmer 

 and Digby, 1907). 



« E.g., Alchetnilla sericata (Murbeck, 1902), Burniannia coelesiis (Ernst aiid Bernard, 

 1912), and Allium odorum (Haberlandt, 1923). 



