1894.] NATURAL SCIENCES OF PHILADELPHIA. 57 



many cases, to reacli the stigma and effect fertilization. The 

 positive fact gained by these observations is that neither humming 

 birds nor bumble bees in any way aid in pollenizing the petal-bear- 

 ing flowers. They are as absolutely self-fertile as the apetalous 

 cleistogene ones. 



An especially interesting ol)servation was the existence of many 

 plants bearing wholly cleistogene flowers among the normal petal- 

 bearing ones. These plants wei'e not as tall or vigorous as the petal- 

 bearers, and could be readily distinguished from a distance by a 

 yellowish-green tint, indicative of imperfect nutrition. It had been 

 before suggested to me by an incidental remark of Mr. Willis in the 

 Proceedings of the Cambridge (England) Philosophical Society, that 

 in some unexplained way there is a relation between imperfect nutri- 

 tion and cleistogamy, — a point which this observation confirms. 



The sum of these observations is, that in Lnpat let} s fidvav arhxtion 

 is innate and not dependent on environment; that bright color and 

 sweet secretions have no relation to the visits of insects; that the 

 petal-bearing flowers are self-fertile, and that cleistogamy is the 

 result of impaired nutrition rather than of any mere labor-saving 

 iuHueuce. 



Apetalism and seed Propulsion in Lamium purpureum. 



Lam ill 1)1 purpureinn, a well-known European species, is some- 

 what common as a weed on my grounds at Germantown, near 

 Philadelphia. It exists in two forms: one with small pale lilac 

 flowers, the other with flowers more rosy and larger. While 

 examining the flowers witii u lens to trace any difference 

 that might exist, I was surprised to have my face peppered 

 by the seeds which had been expelled from the calyx with consider- 

 able force. Examining plants with an abundance of seed vessels, 

 it was seen that most of the calices were empty though still compara- 

 tively erect. The seeds, or properly nutlets, could not easily have 

 fallen out, and doubtless propulsion is the usual method by which 

 they are distributed. 



Examining plants in the early part of July I found large numbers 

 of the upper flowers apetalous. The calyx was perfect, the stamens 

 were of the usual length, and the anthers profusely laden with })ol- 

 len ; the pistil seemed in every respect perfect, but not the 

 slightest trace of corolla existed. The stamens, normally borne on the 

 5 



