. Nature and development of plants. Botany. DEVELOPMENT OF PLANTS 481 The contact of the insect acts as a stimulus, causing the leaves to roll up and so bringing to bear upon him a larger surface of digestive glands. One of the species of Pinguicula is used in northern countries to curdle-milk in place of "rennet" which contains the similar digestive fluids of calves' stomachs. The Potato family (Solanaceae) shows many of the irregu- larities of the figworts, but the majority of its 1,700 species have regular flowers as illustrated in Fig. 334. While the family. Fig. 334. Flower of t
. Nature and development of plants. Botany. DEVELOPMENT OF PLANTS 481 The contact of the insect acts as a stimulus, causing the leaves to roll up and so bringing to bear upon him a larger surface of digestive glands. One of the species of Pinguicula is used in northern countries to curdle-milk in place of "rennet" which contains the similar digestive fluids of calves' stomachs. The Potato family (Solanaceae) shows many of the irregu- larities of the figworts, but the majority of its 1,700 species have regular flowers as illustrated in Fig. 334. While the family. Fig. 334. Flower of the potato {Solanum tuberosum), showing the stamens inserted on the tube of the corolla and encircling the style. is largely tropical, many of the species are cultivated, as the potato, eggplant, tomato, cayenne pepper (Capsicum). Poison- ous, acrid and narcotic properties are characteristic features of the family. Belladonna and atropine from Atropa, stramonium from Datura and nicotine from Nicotiana Tabacum are character- istic drugs. Ground cherry (Physalis), nightshade {Solatium), Petunia, etc., are cultivated forms. 153. A Transitional Order.—It would appear that all the changes possible in the hypogynous type of flowers had been wrought in the members of the Polemoniales and that the next step in advance must be to the epigynous flower. This is seen to be the case with the madder order, Rubiales. Here the flowers are epigynous and the parts are generally in fives though the carpels vary greatly in number. The simplicity in the struc- ture of the flower and often also the form of the inflorescence, as in the elderberry (Sambucus), bedstraw (Galium) and arrow- wood (Viburnum) is strikingly suggestive of the Umbellales (Figs. 335, A, B; 324). It appears that each step in advance is attained in a very simple way and that only gradually are 31. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - colorati
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