Pammel — Anatomical Characters of Seeds oj Leguminosae. 109 



preserved their vitality longer than those of Cruciferae, 

 Compositae, and Gramineae. The imbibition of moisture by 

 the seed, and its drying out, greatly lower its germinative 

 energy, hence the importance of a hard covering (162. 165). 

 Leguminous seeds vary with respect to the amount of water 

 they can take up. It was suggested long ago that this was 

 due to a coating of wax (Nobbe 190, 162). Nobbe and 

 Hanlein (191), and Detmer (56) discuss the subject in all 

 its phases. 



In view of the more recent researches on the nature of the 

 product found in the cuticle, these earlier opinions are not 

 far out of the way. Von Hohnel (115) states that the capac- 

 ity for taking up water resides entirely in the Malpighian 

 cells. The seeds of many Leguminosae^ like Mucuna urens 

 and Cassia Vistula, can withstand immersion in salt water for 

 some time without impairing their vitality. Darwin ( 43a ) long 

 ago noted the fact for several seeds, including some Legu- 

 minosae. Martins (167. 168) and Salter (220) indicate the 

 same facts, and Buchwald (35) has shown how admirably 

 the Malpighian cells of Mucuna and other leguminous strand 

 plants are protected because of the strong development of 

 these cells. Taubert (258) also shows the same general facts. 

 There can scarcely be a doubt that the thick-walled Malpi- 

 ghian cells with their cuticle enable the seed to thus overcome 

 unfavorable conditions. 



It is evident from the above that strand plants may be dis- 

 seminated by ocean currents and that some North American 

 species, e. g. Gleditschia and Gymnocladus^* are disseminated 

 by water. Many of the leguminous seeds are disseminated 

 by herbivorous animals. The Malpighian cells here play no 

 small part in protecting the embryo in the passage of the 

 seed along the digestive tract. I have many times seen cat- 

 tle eat the pods of Gleditschia triacanthos. The sweet gummy 

 material is relished. In Central Iowa it is not uncommon to 

 find the honey locust coming up in the streets and around 

 stables. Warder (281) has mentioned this for Gleditschia. 

 The seed of Prosopis juliflora is largely disseminated by 



* The seed alone is probably rarely carried by the water, except freshets, 

 but the pods aud seeds float. 



