No. 4, January, 1921 1 GENETICS 239 



cells of the stomata. In albo-marginata the epidermis is entirely colorless. In the medio- 

 variegata type the guard-cells are green over hoth the green and white regions. This was 

 also observed in F. ovato f. medio-variegata and /''. lancifolia medio-variegata, while in F . lanci- 

 folia f. albo-jnarginata the epidermis is absolutely colorless. In F. Sieboldiana Hook, medio- 

 variegata there is an average of 18.7 stomata over the white region, and 14.5 over the green 

 region, the stomata being much larger and less elongated over the green regions than over 

 the colorless parts. The opposite is the case in albo-marginata, which averages 12.3 stomata 

 over the green, and 11 over the white regions for the same surface area. — The origin of the 

 variegated Funkia is probably a question of hybrids, the chimeras being of a disjunctive rather 

 than of a periclinal type, some with white epidermis, and some with a green epidermis. — 

 Francena R. Meyer. 



1646. Coe, H. S., and J. N. Martin. Sweet-clover seed. Parti. Pollination studies of 

 seed production. Part II. Structure and chemical nature of the seed coat and its relation to 

 impermeable seeds of sweet clover. U. S. Dept. Agric. Bull. 844. 89 p., 6 fig., 5 pi. 1920. — 

 Brief descriptions are given of development of floral organs, ovules, pollen, and seed of sweet 

 clover, Melilotus alba, mainly, and also M. officinalis. Self-fertilization is as effective as 

 cross-fertilization, judging by length of time elapsing between pollination and fertilization 

 in the two cases and also by comparative rate of embryo development. Pollen germination 

 was 33 per cent in pure water, and from 22 to 64 per cent in cane sugar solutions with strengths 

 from 8 to 45 per cent; germination was best in 12 per cent solution. Pollen tubes made no 

 more growth in sugar solution than in water; so it is concluded that sugar helps in pollen 

 germination by reducing absorption rate of water. There would seem to be no reason per se 

 why pollen germination should not take place freely in the open under wet weather condi- 

 tions; and germination was found to take place under these conditions. — Sweet clover plants 

 protected to prevent access to insects had only 2.9 per cent of the flowers set seed, w r hile 

 unguarded plants had 66.5 per cent. The percentage of cross-pollinated flowers setting seed 

 was 70.1, while the percentage of self-pollinated flowers setting seed was 54.9. Night-flying 

 insects seemed to have but minor effects on fertilization. Many species of insects were 

 found to visit sweet clover. Small insects were found to be efficient pollinators. The honey 

 bee is evidently the most efficient pollinator of sweet clover; species of Haliclus are often 

 nearly as efficient. Excess moisture, in the air or soil, did not affect seed production 

 adversely. Dry soil conditions tended to inhibit seed production. — In histological studies of 

 permeable and impermeable (hard) seeds, the "light line" of Malpighian layer, the chemical 

 nature of which was not determined, was found to be a determining factor. In permeable 

 seeds minute canals were found to traverse the light line radially, allowing water to pass 

 through. These were not visible in impermeable seeds until treated with sulphuric acid, 

 and were then observed to be very small. Seed treatment with acid for one hour did not dis- 

 integrate light line, but rendered seeds permeable. — L. R. Waldron. 



1647. Collins, G. N. Waxy maize from Upper Burma. Science 52:48-51. July 16, 

 1920. — Maize with waxy endosperm has been found in Upper Burma where it is cultivated by 

 uncivilized tribes in the inaccessible mountainous districts. It is grown chiefly for the 

 husks, which are used as wrappers for the enormous cheroots affected by the Burmese. — 

 Plants grown in the United States from the Burma waxy seed were very unlike those raised 

 from the original Chinese waxy seed, but the endosperm texture proved to be genetically 

 identical. — A survey of the region in China where the first waxy seeds were discovered has 

 shown that this type of corn is restricted to a region within 30 miles of Shanghai, and no 

 distinctive Chinese names differentiating the waxy from other types were found. Appar- 

 ently the waxy type has been cultivated in Burma for a longer period, since there is an exten- 

 sive series of named varieties and the distribution is more general. — Waxy endosperm has 

 been found also on the Island of Mindanao by W. H. Weston, but it can not be determined 

 whether the occurrence of this type in the Philippines is the result of a recent introduction 

 from the Chinese source or whether it represents another of the early stations comparable 

 with Burma and Shanghai. — The author believes the waxy endosperm to have originated in 



