1899.] NATURAL SCIENCES OF PHILADELPHIA. 99 



plants. At the same time I had noticed that solitary female plants 

 of Glngho hiloha were fruiting abundantly in Gcrmautown, while the 

 only known male plant was at Woodlands, some ten miles away. 

 Kecently Japan botanists have discovered spiral coils of sperma- 

 tozoids in the generative cells of Giiigko, and others have observed 

 them in Cyccis revoluta. 



The conclusion reached by the author is that though for several 

 years he regarded the Castor-oil plant, Ricinus communis, as a gen- 

 uine case of parthenogenesis, the past year's experience still leaves 

 the matter open to doubt . If it be true that the female flowers of 

 Cycas revoluta can generate spermatozoids in their ovaries, and 

 thus self-fertilize the ova, the occurrence must be rare. In this 

 vicinity old specimens of this plant are frequently seed bearing, 

 opparenthj, but in every case examined by the author thev were 

 found to have only empty capsules. 



It seems to the author that the subject of parthenogenesis is by 

 no means thoroughly " thrashed out," and the object of this paper 

 is to encourage continued observations. 



VIII. LaCTUCA ScARIOLA, in RELATION TO VARIATION AND 

 THE VERTICAL POSITION OF ITS LEAVES. 



Laduca Scariola is spreading rapidly over the United States. 

 Some twenty years ago I was led to my first acquaintance with it 

 through the kindness of Dr. George Engehnann. It Avas then 

 growing in the vicinity of St. Louis. It interested us from the 

 fact that we thought we saw polarity in the leaves. The plane of 

 the leaf was vertical, and it seemed that the edges were directed 

 due north and south. The plants were growing thickly together, 

 and in the cases which did not come under this rule we concluded 

 that the crowding interfered with the natural tendency. Three 

 years ago, 1894, a solitary plant appeared in my garden. The 

 behavior of a species is always instructive when Ave can AA'atch its 

 distribution and development from a single plant A\'ithin a limited 

 area. Being an annual, and floAvering after the garden weeding 

 has been completed, it is a comparatively harmless Aveed. I allowed 

 the plant to seed, and the seeds to be distributed by the Avind. 

 The next season a number of plants were alloAved to seed. This 

 year, 1897, there are hundreds of plants growing Avithin an area of 

 twenty acres. Many of these I am leaA^ing to groAV till they reach 

 the flowering stage, AA'hen they Avill be destroyed. 



