Observations on the Development of Some 



Embryo=sacs. 



{WITFC rZATE XI.) 



By R. E. B. McKenney, B. S. 



THE study of the development of the embryo-sac was 

 suggested to me in the fall of 1897 by Professor J. M. 

 Macfarlane, and has been continued, with interruptions, 

 until the present time. I wish to here acknowledge my in- 

 debtedness to him for suggestions and criticisms of my work. 

 Plants o( Scilla hyacinthoides var cczrulca, S. campanulata, Lilium 

 tigritimn and L. cafididum furnished the material for study. 



Methods. 



As fixatives, I have employed Kleinenberg's Picro-sulphuric, 

 Picro-acetic, Absolute alcohol, and Flemming's strong Chro- 

 mosmo-acetic. The Picric solutions gave veiy good results. 

 Objects not larger than a pea, and with unindurated tissue, 

 will be fixed in an hour. The Picric solutions are best washed 

 out with 50 per cent alcohol. As a clearing fluid I found 

 cedar oil rather better than xylol, since it is less volatile, and 

 seems less likely to cause shrinkage. Care must be taken, 

 however, to have all the cedar oil replaced by pure paraffin, or 

 good sections will not be obtained. The sections were cut 

 on the Minot microtome with a feed of from 6 to 10 /i and 

 fixed to the slide with Mayer's albumen. As staining agents 

 I have used Delafield's Hasmatoxylin, Eosin, Guignard's 

 Methylgreen-Fuchsin, Heidenhain's Iron Haematoxylin and 

 Flemming's triple stain. A combination of Delafield's Haema- 

 toxylin and Eosin proved especially good. 



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